The FCDO has recently updated its policy on providing apostilles on UK birth, marriage certificates.
An apostille is a Government certificate certifying the signature/seal of a public official, in this case a Registrar of births, marriages and deaths. In the past, the FCDO’s Legalisation Office would make checks to verify the registrar’s signature. This will no longer happen. Certified copies of the entry of birth, marriage or death must bear a General Register Office seal in order to be accepted for an apostille.
As before, apostilles will not be affixed to photocopies of such certificates.
To save time that would otherwise be lost where birth, marriage or death certificates are rejected by the Legalisation Office, customers are advised to a obtain a certified copy of the respective entry from the General Register Office – which will have the necessary seal.
Please see: http://www.gov.uk/order-copy-birth-death-marriage-certificate