The title of 'tunnel under Bidston Moss' is misleading. What is being said is that there was a tunnel under the railway line which gave access to Bidston Moss. Good attention grabbing title though
The area around the Triangle, Bidston Moss etc were my stomping ground from when I was 5 (1947) through until maybe 1964.
Access to these area was eithr via Bidson footpath from Mosslands Drive or along the railway embankment from where a bridge crosses the very end of a spur part of Mosslands Drive down alongside (now) Mosslands School.
From the footpath route if you wanted to carry on to Bidston you did have to use a tunnel but for the life of me I cannot now remember where it was. THAT is because us lads generally went along the electric railway embankment from the bridge where the railway crosses over the very end of the "spur" of Mosslands drive alongside Mosslands school.
If we went under
the electric line bridge and turned left along the embankment (difficult ie lots of vegetation) or across the Moss parallel to the electric track (had to beware of the horses & farmer) then eventually you met up with Bidston footpath as it went between "Summers railway) and the Moss.
If we turned left before
the bridge of the elctric line and walked along the northern side of the embankment(much less vegetation) then ultimately you came to the Triangle pond.
However, before you reached the Triangle ther was (and still is) a tunnel (maybe 6ft diameter) that ran under the electric railway at more or less from the bottom of Wallacre playing field. Exactly where I cannot be sure - but may go for a walk tomorrow. In 'my' day a small stream drained from the end of the Mosslands Drive allotments through that tunnel. Water in the tunnel was never more than 6-10" deep and we kids used to use it as a short cut through to Bidston Moss and from where we picked up the Bidston footpathe. Been through hundreds of time I guess.
I can picture this in my mind like it was yesterday