White Pendragons

The White Pendragons are a tiny, Trump-supporting racist group in the UK. They spend their time:
 * trying and failing to perform citizen's arrests of politicians they don't like, such as the Muslim mayor of London,
 * talking about how Anglo-Saxon (i.e. white) English people supposedly invented absolutely everything that is great in the world
 * and pushing deranged conspiracy theories — in particular:
 * freemen on the land theories involving the Magna Carta
 * conspiracy theories that the actually rather moderate Fabian Society is part of some secret extremist plot

People associated with the group have previously been involved with the anti-Muslim English Defence League and the micro-party the English Democrats (not to be confused with the US Democratic Party, with which it has no relationship).

While claiming (probably for legal reasons) that they welcome people of all races and religions, there is no evidence that they are anything other than an all-white, ethnonationalist group.

Khan "arrest"
They purportedly tried to arrest Sadiq Khan in 2018, claiming that he should not be mayor of London "because he is a Muslim" (holding a political office while Muslim is not, needless to say, a crime in the UK). However, in doing so, they demonstrated that they did not know what a was, seemingly believing that it involved calling the police to arrest someone (that is a normal arrest). In reality, it was more of a protest to get media attention, which achieved its objectives, but reporters present had a hard time making sense of who they were or what they wanted from listening to their jumble of wingnut complaints.

They also, disturbingly, brought along a home-made gallows, but hid it out of sight outside, presumably so they would not be arrested for threatening behaviour or similar.