Mr Hilton is one of a close circle of Cameron advisers
The Conservatives have said a close adviser to leader David Cameron was arrested and fined £80 after a dispute at a train station in 2008.
Steve Hilton, the Tories' director of strategy, was briefly detained at Birmingham's New Street station during an annual party conference.
The party has not confirmed reports that Mr Hilton swore at staff.
A former advertising executive, Mr Hilton is regarded as a key figure in the Tory leader's circle.
He is one of a number of key modernising figures closely associated with Mr Cameron since he became party leader in 2005.
A Tory spokesman confirmed the incident - details of which have only now come to light - took place at the end of the party's 2008 autumn conference in Birmingham.
"Steve was in possession of a valid ticket but was unable to produce it quickly enough," he said.
"After British Transport Police intervened a further argument took place and Steve was arrested. Shortly afterwards Steve apologised, was de-arrested and issued with a penalty notice."
In a statement the British Transport Police said: "I can confirm that shortly before 5pm on Wednesday 1 October 2008, a 39-year-old man from London was arrested at Birmingham New Street railway station after a dispute over the production of his ticket.
"Once the man had calmed down, he was issued with a penalty notice for disorder under section five of the Public Order Act."