Well folks, almost three weeks on and the Dulux Trade Eggshell is almost dry. It still feels a bit soft and the fumes on opening the door in the morning are still very strong, although the weather has been good and the door has been open for 10 days with the underfloor heating on too. When Dulux said it would take a week to dry they weren't kidding!
We are very pleased with the final result but would never use Dulux again. Our supplier says he will repeat the job in 6 mths if necessary using his customary paint, he uses another manufacturer because it has much better support with a local depot here.
Thanks again for the helpful advice.