Historic England have released the "Aerial Archaeology Mapping Explorer" which is a must see, it is not complete but has an amazing amount of detail about WW2 structures on the Wirral.

As well as some medieval sites it has:-

Barrage balloon sites
Public street air raid shelters
Public park air raid shelters
Gun sites
Military buildings
Weapons pits
Bomb sites
Ship wrecks
Earthworks
and more

https://historicengland.org.uk/research/results/aerial-archaeology-mapping-explorer/

I can't find a direct link to the map, you have to go through this page to avoid a login script and to pick up a session id. About half way down is "explore the map" in a box.

That seems very interesting, but I may not find my way around it. Probably more of a man's thingy.

Very interesting DD - thanks for posting.

I've just zoomed to my default location, Magazine Village, Bromborough, and found a wreck shown on foreshore there. Measuring it gives 173ft, which is near as dammit to the 175ft length of the old gunpowder hulk 'Swallow'. Looking at a photo I have - it shows the 'Swallow' in exactly the right place, and even depicts the (I think) 'Frollic' alongside in half. Photo is approx 1949, just before the ship was scrapped.
Here's the Aeria Archeology map and the photo:

Wonder if they know what that wreck on their map actually is?

I wonder if Unilever's "Sand Swallow" dredger was also a nod to the gunpowder hulk "Swallow" as well as the obvious self-descriptive name.

This direct link is working.
Map.

Got onto this a bit late. But it looks fantastic. Found interesting info on the Jellicoe watercourse at Cadbury Factory at Moreton and more interesting stuff.

Which is being dug up as we speak, the water feature itself is supposed to be being restored but it will be surrounded by modern houses called Jellicoe Gardens.