Richard sent me a link to a The Register article entitled So, what can you photograph? which relates to the laws surrounding what can, and cannot, be photographed in the UK.

Amongst other facts it says:

As of last week, the government has forbidden couples getting married in registry offices from having their photograph taken as they sign the wedding register.

This was news to me (although Richard has just reminded me that he was asked not to video the registry signing at a recent wedding), but a quick google later and an article Govt bans wedding registry pics shows up, sourcing The Mail, and says

New Government guidelines say photographs of couples signing the register could invade the privacy of others because their signatures may be visible on the same page


and

There are further concerns that details taken from the wedding snaps could be used by fraudsters planning identity theft and that the photos could be in breach of Crown Copyright.

The original Mail article also says

But it seems that the ruling does not affect traditional church weddings. Church of England spokesman Steve Jenkins said: "The focus is always the couple, not the book. It would be obvious if someone started zooming and shooting the book instead.
"I'm not aware of anybody being prevented from taking a photo the couple have requested because of data protection at a church wedding."


which just seems to complicate the matter.