France, May 2 -- Hard-right upstarts Reform UK snatched a parliamentary seat from Prime Minister Keir Starmer's Labour party on Friday in local elections that dealt a blow to Britain's two establishment parties.

Reform, led by anti-immigrant firebrand Nigel Farage, won the by-election in Runcorn and Helsby in northwest England by just six votes, as it picked up gains in other localities including one mayoralty.

The group's strong showing continues momentum it built up at last year's general election and appears to confirm a trend that the UK is entering an era of multi-party politics.

"For the movement, for the party it's a very, very big moment indeed," Brexit champion Farage said of Reform's first-ever by-election win and Starmer's f...