A ticket inspector has been stabbed on a C2C train travelling from Essex into London, prompting an investigation by British Transport Police (BTP).The attack at East Tilbury happened on the 20:20 Southend Victoria to London Fenchurch Street service on Friday.BTP said the inspector had asked two men without tickets, aged about 18, to leave the train. They got off, but one returned and stabbed him in the back.The inspector was said to be in a comfortable condition in hospital.Officers are now looking through CCTV images and are appealing to any passengers on the train who witnessed anything to contact them.One of the suspects wore a black hooded top and the second a grey flat cap and grey top.The police force said there had been four ticket inspectors on the service at the time of the stabbing and that they worked in pairs.Bob Crow, general secretary of the Rail Maritime and Transport union representing many railway workers, said anyone with any information should contact police urgently.\"Once again it shows the dangers that transport staff face every day and particularly over the Christmas and new year period.\"The perpetrators of this vicious and cowardly assault must be caught and the authorities need to show that those who attack public service workers will be severely punished,\" he said.