In article , Peter
writes
Thank you all for you advice, much appreciated.

Peter

And I should ignore most of it. The critical questions a
1. Is the lawn so wet that working on it or moving machinery across it
would damage it?
2. Are frosts imminent?
If the answer to both is no then I would go ahead and scarify. Getting
rid of moss and dead grass (thatch) will do more good than harm. Grass
is very resilient although it will look a bit of a mess for a while if
you can't get on it later to cut it - see points 1 and 2 above again.
--
hugh