"Sue & Bob Hobden" wrote in message
...

I've found a picture of one and it wasn't it. Shell was very like a normal
garden snail in shape, not elongated, and was (worn?) white where the
snail
wasn't living. Actual animal was perfect, rather beautiful, and grey in
colour.

Then perhaps it was a Roman Snail, Helix pomatia; but I wouldn't have called
this 'huge' in quite the terms you used - it's about half as big again as
the garden snail Helix aspersa. There are other similar large snails from
farther afield such as Helix lucorum, but I don't know of any of these
actually living in the wild in the UK.