DBRS Morningstar Upgrades and Confirms Ratings on Durham Mortgages B plc

DBRS Ratings Limited (DBRS Morningstar) took the following rating actions on the notes issued by Durham Mortgages B plc (the Issuer):

-- Class A Notes confirmed at AAA (sf)
-- Class B Notes confirmed at AA (low) (sf)
-- Class C Notes confirmed at A (low) (sf)
-- Class D Notes confirmed at BBB (sf)
-- Class E Notes confirmed at BB (sf)
-- Class F Notes confirmed at B (sf)
-- Class X Notes upgraded to BB (sf) from B (sf)

The rating on the Class A Notes addresses the timely payment of interest and the ultimate payment of principal by the legal final maturity date in November 2054. The rating on the Class B Notes addresses the ultimate payment of interest and principal, and the timely payment of interest while the senior-most class outstanding. The ratings on the Class C, Class D, Class E, Class F, and Class X Notes address the ultimate payment of interest and principal.

The upgrade and confirmations follow an annual review of the transaction and are based on the following analytical considerations:
-- Portfolio performance, in terms of delinquencies, defaults, and losses, as of the May 2022 payment date;
-- Portfolio default rate (PD), loss given default (LGD), and expected loss assumptions on the remaining receivables;
-- Current available credit enhancement to the notes to cover the expected losses at their respective rating levels.

The Issuer is a securitisation of buy-to-let residential mortgages originated by Bradford & Bingley plc, Mortgage Express, GMAC, Kensington Mortgages Limited, and Close Brothers Group plc; sold by Cornwall Home Loans Limited; and serviced by Topaz Finance Limited (Topaz).

PORTFOLIO PERFORMANCE
As of the May 2022 payment date, loans two to three months in arrears represented 0.4% of the outstanding portfolio balance and loans at least three months in arrears represented 1.5% of the outstanding portfolio balance. Cumulative net losses were 0.1%.

PORTFOLIO ASSUMPTIONS AND KEY DRIVERS
DBRS Morningstar conducted a loan-by-loan analysis of the remaining pool of receivables and updated its base case PD and LGD assumptions at the B (sf) rating level to 7.1% and 19.3%, respectively.

CREDIT ENHANCEMENT
As of the May 2022 payment date, credit enhancement to the Class A, Class B, Class C, Class D, Class E, and Class F Notes was 17.4%, 13.0%, 9.3%, 6.0%, 3.6%, and 2.1%, respectively, up from 15.8%, 11.8%, 8.4%, 5.4%, 3.2%, and 1.9%, respectively, at the time of DBRS Morningstar’s initial rating. Credit enhancement is provided by subordination of the junior notes and the general reserve fund. The Class X Notes do not benefit from hard credit enhancement in the form of subordination, but are paid down through the use of available excess spread. To date, the Class X Notes have been paid down to GBP 16.1 million, from GBP 26.2 million at transaction close.

The transaction benefits from a liquidity reserve fund, which covers senior fees and interest on the Class A Notes. The liquidity reserve fund is funded to its target level of GBP 7.5 million, equal to 0.5% of the Class A Notes’ initial balance.

The general reserve fund is nonamortising and covers senior fees, interest on the Class A to Class F Notes (where the Class B to Class F Notes are subject to a principal deficiency ledger (PDL) condition of 10%), and principal losses via the PDLs on the Class A to Class F Notes. The general reserve fund is funded to its target balance of GBP 21.9 million, equal to 1.25% of the initial portfolio balance.

Citibank N.A./London Branch (Citibank London) acts as the account bank for the transaction. Based on DBRS Morningstar’s private rating on Citibank London, the downgrade provisions outlined in the transaction documents, and other mitigating factors inherent in the transaction structure, DBRS Morningstar considers the risk arising from the exposure to the account bank to be consistent with the rating assigned to the Class A Notes, as described in DBRS Morningstar's "Legal Criteria for European Structured Finance Transactions" methodology.

DBRS Morningstar analysed the transaction structure in Intex DealMaker.

ENVIRONMENTAL, SOCIAL, GOVERNANCE CONSIDERATIONS
There were no Environmental/Social/Governance factors that had a significant or relevant impact on the credit analysis.

A description of how DBRS Morningstar considers ESG factors within the DBRS Morningstar analytical framework can be found in the DBRS Morningstar Criteria: Approach to Environmental, Social, and Governance Risk Factors in Credit Ratings at https://www.dbrsmorningstar.com/research/396929/dbrs-morningstar-criteria-approach-to-environmental-social-and-governance-risk-factors-in-credit-ratings.

Notes:
All figures are in British pound sterling unless otherwise noted.

The principal methodology applicable to the ratings is the “Master European Structured Finance Surveillance Methodology” (19 May 2022).

Other methodologies referenced in this transaction are listed at the end of this press release. These may be found at: https://www.dbrsmorningstar.com/about/methodologies.

DBRS Morningstar has applied the principal methodology consistently and conducted a review of the transaction in accordance with the principal methodology.

A review of the transaction legal documents was not conducted as the legal documents have remained unchanged since the most recent rating action.

For a more detailed discussion of the sovereign risk impact on Structured Finance ratings, please refer to “Appendix C: The Impact of Sovereign Ratings on Other DBRS Morningstar Credit Ratings” of the “Global Methodology for Rating Sovereign Governments” at: https://www.dbrsmorningstar.com/research/381451/global-methodology-for-rating-sovereign-governments.

The DBRS Morningstar Sovereign group releases baseline macroeconomic scenarios for rated sovereigns. DBRS Morningstar analysis considered impacts consistent with the baseline scenarios as set forth in the following report: https://www.dbrsmorningstar.com/research/384482/baseline-macroeconomic-scenarios-application-to-credit-ratings.

The sources of data and information used for these ratings include investor reports provided by Citibank N.A./London Branch and loan-level data provided by Topaz Finance Limited.

DBRS Morningstar did not rely upon third-party due diligence in order to conduct its analysis.

At the time of the initial ratings, DBRS Morningstar was supplied with third-party assessments. However, this did not impact the rating analysis.

DBRS Morningstar considers the data and information available to it for the purposes of providing these ratings to be of satisfactory quality.

DBRS Morningstar does not audit or independently verify the data or information it receives in connection with the rating process.

The last rating action on this transaction took place on 19 August 2021 when DBRS Morningstar finalised its provisional ratings on the Class A, Class B, Class C, Class D, Class E, Class F, and Class X Notes at AAA (sf), AA (low) (sf), A (low) (sf), BBB (sf), BB (sf), B (sf), and B (sf), respectively.

The lead analyst responsibilities for this transaction have been transferred to Clare Wootton.

Information regarding DBRS Morningstar ratings, including definitions, policies, and methodologies, is available at www.dbrsmorningstar.com.

Sensitivity Analysis: To assess the impact of changing the transaction parameters on the ratings, DBRS Morningstar considered the following stress scenarios as compared with the parameters used to determine the ratings (the Base Case):

-- DBRS Morningstar expected a lifetime base case PD and LGD for the pool based on a review of the current assets. Adverse changes to asset performance may cause stresses to base case assumptions and therefore have a negative effect on credit ratings.
-- The base case PD and LGD of the current pool of loans for the Issuer at the B (sf) rating level are 7.1% and 19.3%, respectively.
-- The risk sensitivity overview below illustrates the ratings expected if the PD and LGD increase by a certain percentage over the base case assumption. For example, if the LGD increases by 50%, the rating of the Class A Notes would be expected to fall to AA (low) (sf), assuming no change in the PD. If the PD increases by 50%, the rating of the Class A Notes would be expected to fall to A (high) (sf), assuming no change in the LGD. Furthermore, if both the PD and LGD increase by 50%, the rating of the Class A Notes would be expected to fall to BBB (high) (sf).

Class A Notes Risk Sensitivity:
-- 25% increase in LGD, expected rating of AA (sf)
-- 50% increase in LGD, expected rating of AA (low) (sf)
-- 25% increase in PD, expected rating of AA (sf)
-- 50% increase in PD, expected rating of A (high) (sf)
-- 25% increase in PD and 25% increase in LGD, expected rating of A (high) (sf)
-- 25% increase in PD and 50% increase in LGD, expected rating of A (sf)
-- 50% increase in PD and 25% increase in LGD, expected rating of A (low) (sf)
-- 50% increase in PD and 50% increase in LGD, expected rating of BBB (high) (sf)

Class B Notes Risk Sensitivity:
-- 25% increase in LGD, expected rating of A (high) (sf)
-- 50% increase in LGD, expected rating of A (low) (sf)
-- 25% increase in PD, expected rating of A (sf)
-- 50% increase in PD, expected rating of A (low) (sf)
-- 25% increase in PD and 25% increase in LGD, expected rating of A (low) (sf)
-- 25% increase in PD and 50% increase in LGD, expected rating of BBB (high) (sf)
-- 50% increase in PD and 25% increase in LGD, expected rating of BBB (high) (sf)
-- 50% increase in PD and 50% increase in LGD, expected rating of BBB (sf)

Class C Notes Risk Sensitivity:
-- 25% increase in LGD, expected rating of BBB (high) (sf)
-- 50% increase in LGD, expected rating of BBB (sf)
-- 25% increase in PD, expected rating of BBB (high) (sf)
-- 50% increase in PD, expected rating of BBB (sf)
-- 25% increase in PD and 25% increase in LGD, expected rating of BBB (sf)
-- 25% increase in PD and 50% increase in LGD, expected rating of BBB (low) (sf)
-- 50% increase in PD and 25% increase in LGD, expected rating of BB (high) (sf)
-- 50% increase in PD and 50% increase in LGD, expected rating of BB (high) (sf)

Class D Notes Risk Sensitivity:
-- 25% increase in LGD, expected rating of BB (high) (sf)
-- 50% increase in LGD, expected rating of BB (high) (sf)
-- 25% increase in PD, expected rating of BB (high) (sf)
-- 50% increase in PD, expected rating of BB (high) (sf)
-- 25% increase in PD and 25% increase in LGD, expected rating of BB (high) (sf)
-- 25% increase in PD and 50% increase in LGD, expected rating of BB (sf)
-- 50% increase in PD and 25% increase in LGD, expected rating of BB sf)
-- 50% increase in PD and 50% increase in LGD, expected rating of BB (low) (sf)

Class E Notes Risk Sensitivity:
-- 25% increase in LGD, expected rating of BB (low) (sf)
-- 50% increase in LGD, expected rating of B (high) (sf)
-- 25% increase in PD, expected rating of BB (low) (sf)
-- 50% increase in PD, expected rating of B (high) (sf)
-- 25% increase in PD and 25% increase in LGD, expected rating of B (high) (sf)
-- 25% increase in PD and 50% increase in LGD, expected rating of B (sf)
-- 50% increase in PD and 25% increase in LGD, expected rating of B (sf)
-- 50% increase in PD and 50% increase in LGD, expected rating below B (low) (sf)

Class F Notes Risk Sensitivity:
-- 25% increase in LGD, expected rating below B (sf)
-- 50% increase in LGD, expected rating below B (sf)
-- 25% increase in PD, expected rating below B (sf)
-- 50% increase in PD, expected rating below B (sf)
-- 25% increase in PD and 25% increase in LGD, expected rating below B (sf)
-- 25% increase in PD and 50% increase in LGD, expected rating below B (sf)
-- 50% increase in PD and 25% increase in LGD, expected rating below B (sf)
-- 50% increase in PD and 50% increase in LGD, expected rating below B (sf)

Class X Notes Risk Sensitivity:
-- 25% increase in LGD, expected rating of BB (low) (sf)
-- 50% increase in LGD, expected rating of B (high) (sf)
-- 25% increase in PD, expected rating of BB (low) (sf)
-- 50% increase in PD, expected rating of B (high) (sf)
-- 25% increase in PD and 25% increase in LGD, expected rating of B (high) (sf)
-- 25% increase in PD and 50% increase in LGD, expected rating of B (high) (sf)
-- 50% increase in PD and 25% increase in LGD, expected rating of B (sf)
-- 50% increase in PD and 50% increase in LGD, expected rating below B (sf)

For further information on DBRS Morningstar historical default rates published by the European Securities and Markets Authority (ESMA) in a central repository, see: http://cerep.esma.europa.eu/cerep-web/statistics/defaults.xhtml. DBRS Morningstar understands further information on DBRS Morningstar historical default rates may be published by the Financial Conduct Authority (FCA) on its webpage: https://www.fca.org.uk/firms/credit-rating-agencies.

These rating are endorsed by DBRS Ratings GmbH for use in the European Union.

Lead Analyst: Clare Wootton, Vice President
Rating Committee Chair: Alfonso Candelas, Senior Vice President
Initial Rating Date: 16 August 2021

DBRS Ratings Limited
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London EC3M 3BY United Kingdom
Tel. +44 (0) 20 7855 6600
Registered and incorporated under the laws of England and Wales: Company No. 7139960.

The rating methodologies used in the analysis of this transaction can be found at: https://www.dbrsmorningstar.com/about/methodologies.

-- Legal Criteria for European Structured Finance Transactions (22 July 2022), https://www.dbrsmorningstar.com/research/400166/legal-criteria-for-european-structured-finance-transactions.
-- Master European Structured Finance Surveillance Methodology (19 May 2022), https://www.dbrsmorningstar.com/research/397033/master-european-structured-finance-surveillance-methodology.
-- Operational Risk Assessment for European Structured Finance Servicers (16 September 2021), https://www.dbrsmorningstar.com/research/384513/operational-risk-assessment-for-european-structured-finance-servicers.
-- European RMBS Insight Methodology (28 March 2022) and European Asset RMBS Insight Model v5.6.0.0, https://www.dbrsmorningstar.com/research/394309/european-rmbs-insight-methodology.
-- European RMBS Insight: UK Addendum (27 October 2021),
https://www.dbrsmorningstar.com/research/386599/european-rmbs-insight-uk-addendum.
-- Interest Rate Stresses for European Structured Finance Transactions (24 September 2021), https://www.dbrsmorningstar.com/research/384920/interest-rate-stresses-for-european-structured-finance-transactions.
-- DBRS Morningstar Criteria: Approach to Environmental, Social, and Governance Risk Factors in Credit Ratings (17 May 2022),
https://www.dbrsmorningstar.com/research/396929/dbrs-morningstar-criteria-approach-to-environmental-social-and-governance-risk-factors-in-credit-ratings.

A description of how DBRS Morningstar analyses structured finance transactions and how the methodologies are collectively applied can be found at https://www.dbrsmorningstar.com/research/278375.

For more information on this credit or on this industry, visit www.dbrsmorningstar.com or contact us at info@dbrsmorningstar.com.