Broadcaster Jeremy Vine has begun a High Court defamation fight with a former local radio presenter who operates a YouTube channel.
Mr Vine, a BBC Radio 2 presenter, is suing Alex Belfield, saying he defamed and harassed him on YouTube and Twitter between May and August 2020.
Mr Belfield is disputing claims made against him.
A judge oversaw a preliminary hearing at the High Court in London on Tuesday.
Mr Justice Nicklin considered legal issues and made no rulings on any issues.
Mr Vine was at the hearing.
The judge heard that Mr Belfield was a former local radio presenter who operated a YouTube channel called Alex Belfield – The Voice Of Reason.