This SS has not yet been added to the PRA Rulebook. It is available on the Bank of England website, here.

https://www.bankofengland.co.uk/prudential-regulation/publication/2015/the-uk-leverage-ratio-framework-ss

Related links

Leverage Ratio (CRR)
Leverage Ratio – Capital Requirements and Buffers
Third Country Branches
PS5/23 - Risks from contingent leverage https://www.bankofengland.co.uk/prudential-regulation/publication/2023/may/risks-from-contingent-leverage