Methodology: Insider Intelligence benchmarks its mortgage debt balance figures against Bank of England Mortgage Lenders and Administrators Return data, for which the last full year measured was 2021. A regulated loan is a loan to an individual secured by a first charge on residential property, and where the property is for the use of the borrower or a close relative. Second-charge lending was included in nonregulated lending until March 20, 2016, and has since been included in regulated lending. A nonregulated loan is all other mortgage lending to individuals that is not regulated. It includes buy-to-rent lending, and, in some cases, further advances on loans that were originally taken out before regulation came into effect on October 31, 2004.