Started in 1966, the first tube of the 1.5 mile road tunnel between Wallasey and Liverpool took five years to build and was opened by the Queen on June 24, 1971.

Consultants recommended a six-lane bridge which, according to Kingsway architect Tom Harker, would have rivalled San Francisco’s Golden Gate Bridge. But the tunnel – unlike the bridge – could be constructed in phases, helping to manage cost and the wider impacts and it could also link to Wirral’s M53 motorway using an old railway cutting for the Wallasey approach road.

A short section on the Liverpool side had to be excavated through clay using different methods.