Henson, 24, was travelling back to Cardiff after a staring role in the Ospreys EDF Energy Cup victory away to Harlequins that day.

Passengers on the train claim they suffered almost two hours of “hell” as Henson and friends played violent drinking games.

All four men were later questioned by British Transport Police when the train arrived at Cardiff.

The rugby star, who has a child with Welsh singer Charlotte Church, is also facing a separate investigation from the Ospreys.

Now it has emerged that Henson and his friends were questioned under caution on Thursday accompanied by their solicitors.

“All four men attended for interview at a British Transport Police (BTP) office in Cardiff on Thursday morning, accompanied by their solicitors,” a BTP spokesman said today.

The questioning followed completion of a file containing all the available witness statements to the alleged incident.

All four had been reported for disorderly conduct and using abusive, insulting words likely to cause harassment, alarm and distress, contrary to Section 5 of the Public Order Act 1986.

“As is normal practice when all the evidence in a case is complete a file is put together and a disposal, whether or not to prosecute, decision is made,” the spokesman added.

“That decision will probably be made some time tomorrow.”