BOURNEMOUTH, England (Reuters) - Nigel Farage bowed out as leader of Britain's UK Independence Party by enjoying a naked swim in the sea, according to the party's main donor who also took part in the skinny dipping escapade.

Businessman Arron Banks said he and Farage, who was replaced by Diane James as leader of the anti-EU party on Friday, had stripped off for the swim on Thursday night in Bournemouth on England's south coast where the party is holding its conference.

"We had dinner last night, a few drinks, it was late at night and we went skinny dipping off the Bournemouth Pier," Banks told BBC radio late on Friday. "If ever a man's about to leave British politics, that's it."

The news provoked much amused comment on social media while opposition Labour lawmaker Angela Eagle who was on the same radio program said: "What a revolting image. I think there should be a law against it."

It's not the first time Farage has taken part in naked swimming. He admitted last year he had gone skinny dipping in the English Channel in his youth in the middle of the night.

(Reporting by William James and Michael Holden; Editing by Gareth Jones)