The East Coast rail line runs from London to Scotland's major cities, including Edinburgh, Aberdeen and Glasgow.
Over three years ago the line had to be nationalised because operator National Express revealed it couldn't afford to pay the franchise. The company was commited to a £1.4 billion contract.
No formal bidders have yet been confirmed, but it could reignite competition between Virgin Trains and FirstGroup who went head-to-head to run the West Coast line.
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