Freedom Alliance, they call themselves here. I went and dug up their web site, which smells strongly of American Libertarian. Starts off sounding quite reasonable if you don’t know their catchphrases, then it gets a bit iffy, then “the Bank of England shouldn’t have a monopoly on printing money”…
The mask denial isn’t mentioned there, incidentally. Though their local candidate (who’s standing for parish council too) gave her party affiliation as “Freedom Alliance - No More Lockdowns” which is a bit of a clue even without having to look at actual news.