Separate topics are now getting combined here. The connection to credit card fraud JohnMacWW is to the original topic of being asked for photo ID.
The topic of UK immigration is a spin-off topic that has nothing to do with the original topic of photo ID.
Mandolino, every country refuses entry to people who have valid documents, proof of funds and return tickets. Why would you question that at all?
A common phrase used on various countries Immigration pages says, 'satisfy the Immigration Officer of your intentions.' That phrase is often used as the sole justification by airlines for insisting you buy a return ticket even when a country actually has no real rule that insists you have one. Canada is an example I am aware of.
But any Canadian Border Services agent can deny anyone entry if they are not 'satisfied' with your stated intentions. There is a TV reality series showing them doing exactly that, on the National Geographic Channel.
http://www.natgeotv.com/ca/border-security
No one other than a citizen of a country has a RIGHT to enter the country. It is entirely up to Immigration to decide whether to let you enter or not regardless of your documentation, money or return tickets.
Basically it's simple. They only have to SUSPECT you of something to decide to deny you entry. So I see no point in asking GUWonder for specifics.