".... Thanks. It is clay. The turf was laid by our own contractor after
we moved in. Is the builder supposed to prepare the ground beforehand? Who
is to blame? ...."

No one. Its just the exceptional dry weather.
I have a few cracks in grassland that is on a good loam.

If you are worried then fill with concrete sand, this will help with
drainage when we have a wet spell. easier than spiking later.


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