Judges at London’s High Court have thrown out an attempt to prosecute Boris Johnson, the frontrunner to succeed Theresa May as prime minister, for allegedly lying about Brexit during the 2016 EU referendum campaign.

But at a judicial review hearing on Friday at the High Court, Johnson’s lawyer Adrian Darbishire said that judge had either erred in law or provided the wrong legal test in allowing the case to go ahead.

Darbishire said the only rational conclusion was that the case was politically motivated and therefore vexatious.

“For the avoidance of doubt, it is denied by the Claimant that he acted in any way improperly or dishonestly. Public debate about the accuracy or otherwise of the £350m continues to this day,” Johnson’s lawyers said in a court document.

The case revolved around a claim famously emblazoned on Johnson’s “Leave” campaign bus that Britain would be 350 million pounds a week better off outside the EU.

Marcus Ball, 29, had tried to prosecute Johnson for misconduct in a public office and last month, a judge said Johnson must appear in court over the allegation.

The High Court judges said they would give the reasons for throwing out the case at a later date.Ball said he was considering whether to appeal and would wait to see the judgement.“I will not give up until I believe that all possible options are exhausted,” he said.