from Dixons Marriage Cert tutorial ...
http://home.clara.net/dixons/Certificates/marriages.htmNames of Bride and Groom
Column two is the name and surname of the bride and groom at the date of the marriage. Those last 6 words are crucial - the name used at the date of marriage is not necessarily the one on the birth certificate of the bride or groom. These days the words "Name changed by Deed Poll" or "formerly known as ................." or "otherwise" indicate that the bride or groom has changed their name since birth but that is a fairly recent phenomenon. In the past, the bride or groom were simply asked for the names they were known by. Remember that it was not necessary to produce any proof of the use of a name.
Names were changed in all sorts of ways. One of the most common would be by the bride or groom using a stepfathers surname. Or a person might use a mothers maiden name or indeed a name chosen at random because they didn't like the one they were born with or because they wanted their original identity hidden for a variety of reasons.
First names also frequently changed - the child named Albert Henry is always known as James for some reason and that is the name he marries in.
In theory it should be possible to use the column showing fathers name and surname as a guide to the original surname of the bride or groom but fathers details too are not always accurate.