All - thanks for the advice!

Seems there is a difference of opinion as to what the outcome may be -
currently all I have right now is the soil covering the old lawn - we
haven't arranged a date for the new turf to be laid.

One thing I would say regarding the waterlogging issue is that we live on
the coast and our soil is sandy and drainage has never been a problem so
far. I was thinking more about the decomposition of the underlying turves
and what that might do to the new root system..

On the other hand, if it was good enough for Steve's father....

Decisions, decisions....

Thanks again.
David