Time for some patriotic Brits to organize a campaign where folks publicly pledge to rush to the defense of any uniformed serviceman being harrassed. Get a slogan like “I’m Standing with Tommy” or something. Backing down and hiding is exactly the wrong approach and is terribly un-British.
Might be embarrassed to find how few would join. Things have changed.
I was in Hyde Park in the seventies. A "speaker" got up on a box (I don't know if was a soap box) and started to rant against the US. I was getting really upset with him but held off on comments. Before I could get engaged with him the crowd started questioning him and ridiculing his statements to the extent that he took his box and left.
I didn't realize until later that it was the forth of July. One of the locals I was talking with pointed it out when he found out that I was from "the colonies." I waited around for the fireworks display but they never started.