Lost compression - after head change

[Bob Olive]

Thanks everyone. I have removed the head this morning and can see nothing wrong. I'll try the wet test - and do a compression test as suggested.
The car was running very well prior to this minor incident which makes it all rather odd.
I'll report back.
Derek, thanks for the offer I'll bear it in mind, although I have always been keen on a HC head to go with the Phoenix crank, Renault rods etc set-up.