The Chancellor George Osborne was accused last night of sitting in the first class carriage of a busy London-bound train with a standard class ticket.
ITV Granada reporter Rachel Townsend, who was sitting nearby, witnessed Mr Osborne's aide negotiating with a ticket collector to allow him to remain there without paying extra.
The ticket collector allegedly told the aide that the Chancellor would be required to upgrade his ticket if he wished to remain in that carriage.
After initially refusing to pay the extra £160, she reports, Mr Osborne finally conceded and paid the difference to apparently settle the dispute and remain in first class.
As a result of our reporter tweeting the incident, a small crowd of press was awaiting Mr Osborne when Virgin Trains' 15.11 service from Wilmslow arrived at Euston station. Mr Osborne refused to answer questions from journalists.
Critics were quick to comment on the incident, with Labour MP Michael Dugher likening the Chancellor's actions to those of Andrew Mitchell in the "pleb" scandal.
While Bob Crow, leader of the RMT rail union, released a statement that said: "Here we have a millionaire Chancellor who thinks he's above the normal rules and laws."
The Treasury told ITV News the incident arose after the Chancellor and his aide were forced to take a different train to the one they had been scheduled to travel on due to a diary change, and their existing seat reservations did not apply.
The Treasury claimed that the train was crowded, so the pair decided to upgrade from standard class to first class and they had always intended to pay the difference, adding that the Chancellor was unaware of any row with a ticket officer.
Virgin Trains released a statement saying that the incident had been dealt with amicably between the train manager and the aide and claimed that "at no time was there a disagreement or a refusal to pay for the upgrade."
Meanwhile, Twitter user @LarryLarryLal retweeted a post they had written in May that claimed they were on the same train as Mr Osborne when the Chancellor tried to avoid paying the correct first class fare.