The United Kingdom Country Signing Certificate Authority (CSCA)
Information on the CSCA operated by His Majesty’s Passport Office.
HM Passport Office produces United Kingdom (UK) passports signed as GBR and Bermuda passports signed on behalf of Bermuda as BMU.
You can contact us by email: document.technology@homeoffice.gov.uk
GBR passport CSCA
CSCA certificates
Certificate Revocation List (CRL)
https://hmpo.gov.uk/csca/GBR.crl