RMT union members on the Caledonian Sleeper train service between London and Scotland struck for 48 hours just before Christmas last year.
The workers were striking over operator Serco’s failure to address a number of defects contained within the rolling stock.
The union said some defects are potentially dangerous to staff and passengers on a service that is unreliable and riddled with health, safety and welfare issues.
It emerged during the strike that Serco would be reimbursed around £300,000 in lost profits by the Scottish government under contract rules.
It was also revealed that £5 million was blown on consultancy and tendering costs before the contract was awarded to Serco in March last year.