That requires a Tory victory in February '74, Wilson had already committed to scrap the Chunnel if he returned to No 10. A Tory win requires less Liberal votes and much better domestic governance from the Grocer. You'd need a 1970 POD to make that work out. A Tory victory in October '74 is ASB. IOTL it was the joint political muscle of Thatcher and Mitterrand that allowed the Chunnel to be built.