https://en.wikipedia.org/wiki/Ernst_Z%C3%BCndel

On 5 February 2003, Ernst Zündel was detained by local police in the U.S. and deported to Canada, where he was detained for two years on a security certificate for being a foreign national considered a threat to national security pending a court decision on the validity of the certificate. Once the certificate was upheld, he was deported to Germany and tried in the state court of Mannheim on outstanding charges of incitement of Holocaust denial dating from the early 1990s. On February 15, 2007, he was convicted and sentenced to the maximum term of five years in prison. All these imprisonments and prosecutions were for inciting hatred against an identifiable group.[9] He was released on March 1, 2010.[10]

If they even TRY with Americans then Trump would grandstand telling them to get fucked to their face.I can think of NO country, not even Canada or Australia or even the EU, that would extradite it's citizens for 'breaking UK speech laws'.

It wouldn’t be totally without precedent… though I suppose Zundel’s citizenship status complicated things, he had been a resident of Canada from 1958-2000