I don't know a lot about the who-can-marry-people regulations, but I do know that DSIL2, who was ordained into the Anglican/Episcopalian Church (long story, no time for it right now) also has the same certificate as a registrar, to let him perform marriages. I believe that in England it is the place that is licensed, so if you are married anywhere that does not have a licence it has also ratified civilly, using the celebrant's signature as evidence.
However, in Scotland the place does not matter, it is the person who is licensed. That is how Madonna could marry in a remote castle, and my friends's son could marry in the Balmoral Hotel (the ceremony conducted by an old family friend who also happens to be licensed).