It has been reported that the RMT has started legal proceedings against London Mayor candidate, Boris Johnson, over a poster being used as part of his election campaign.

The “Not Ken Again” poster, first appeared last month and allegedly portrays RMT leader, Bob Crow, as “corrupt, venal and scandalous” – and despite the union calling on Mr Johnson’s re-election campaign to withdraw them, saying: “ur opinion is that this poster falsely portrays Bob Crow and RMT as part of some corrupt, venal, scandalous and wasteful group of cronies associated with Ken Livingstone.

“It also seems to portray Bob Crow and RMT as supporters of Ken Livingstone when the truth is that Bob Crow has not supported Mr Livingstone’s campaign as a Labour Candidate for Mayor, is not a member or supporter of the Labour Party and RMT is not affiliated to the Labour Party.”

Having originally called on the posters to be removed; the transport workers’ union have this week announced that it has launched a High Court defamation case over the poster, with a spokesperson adding: “RMT can confirm that we have today commenced a High Court action for defamation on Boris Johnson over his Not Ken Again poster campaign which falsely portrays our General Secretary Bob Crow as being part of a culture of political immorality and as having caused serious harm to the interests of people in London.”

Following the revelations that RMT are to take legal action, a spokesperson for Boris Johnson said: “Boris has instructed his solicitors that he intends to robustly defend this baseless claim.”