It no longer costs more to specify conditions on a certificate application to the GRO. All certificates are now £9.25 including postage. The procedure for specifying conditions is a little clunky, though. You need to say "no" to the question "is the GRO reference known" (even if you do know it). You then get directed to a screen which allows you to enter things like a parent's name. If there is no match, your fee is refunded in full. Certificates ordered this way take a little longer - 15 days from order to despatch rather than 4.