I have been in London many times, but this particular time when I was living there, I was at Oxford for school.
I was living at Trinity, so not far from that cross in the street where the Oxford Martyrs were burned. And of course seeing and hearing a lot about the Oxford Movement and finding books in the bookstores detailing various anti-Catholic historic riots and such that were not so discussed in the USA.
It was not so much with the people from Oxford University itself (which is in any event overrun with Americans in the summer, or was then, and I ran into more anti-US sentiment than I did anti-Catholic sentiment) but more in the town. I didn’t get the worst of it because I was only a sporadic churchgoer, but one of the girls on summer study with me was closer to being a traditional Catholic and she ran into some of it. I don’t think it was universal among all the people who lived there either but it was just enough to make me think. Although I wasn’t happy about people being burned either and that made me think too.