Originally Posted by
samwise6222
Happened to me in London too as a US passport holder transiting, but he relented after I was able to convince him that I had enough time to go to Windsor Castle and make it back.
But he gave me a different stamp compared to every other UK stamp I have a leave to enter for 24 hour stamp - and every time I go back to the UK, border agents ask me what I did to get that stamp.
you are the first person I have seen to have that same stamp. Our family of 4 was let in for just a few hours and we got the same stamp.