Thanks for your replies. Did them all again with the water-based undercoat and then the Diamond eggshell. Had no problems applying it to 11 doors/frames.
Gilbert
I have just applied Dulux High Gloss brilliant white to several internal doors, which all had yellowing. After reading this forum I think I should have applied Diamond Eggshell, which I shall be using for the remaining doors, particularly the Bathroom doors.
If I decide to repaint the doors...