There's an interesting article on the Alan Godfrey Maps website about the various schemes for Mersey crossings ...

http://www.alangodfreymaps.co.uk/Parrott1.htm

Just a thought - the first Mersey tunnel was probable built using 'pick axe and shovels' hard work back then!

Funnily enough the first tunnel, the railway tunnel in the 1880s, used a boring machine whereas the Queensway tunnel in the 1920s didn't. I've never understood this anomaly.

1920s lots of unemployment, so lots of men got work on the tunnel, still been worked on in early 30s. Possible reason by the city fathers to help with the unemployment at the time