I found the solution!
After posting my question, checking the manual, searching on-line And asking my supplier, I called up NEFF technical support. They eventually came up with the answer:-
The flashing 'circle and water drop' symbol is a prompt for you to run the 'FLUFF CLEAN CYCLE". Its actually detailed on p14 of my manual but there is no mention of 'cln' coming up. Its under Special cycles NOT under Trouble Shooting or 'error codes' where I would have expected it.
Ran this and flashing lights all gone!
Hope this helps someone else.