Mathew wrote "....I have several sacks of garden soil that I need to get
rid of, and will have some more when I dig my pond foundations (next
weekend?)
I'd offer it up for grabs, but it really is awful stuff - mostly clay and
rubble ........."

One answer is to dig a hole and bury it.

Not as stupid as it sounds.........you say you are going to dig a pond, then
why not remove the top soil that is usable, then use the clay to either
raise the level around the sides(This way you don't have to dig it so deep)
or raise a bank on one side of the pond and use the Top soil to cover it.
Years ago I dug a pool 30ft x 30 x30 (Yes it was triangular) and raised an
island in the middle with some of the clay and a bank on the North side with
the rest.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk