There is no manual over ride to open the door on this model. However a very helpfull engineer at Electrolux / Zanussi told me how to open the door.
Tease a strong length of string under the door between the door and the body of the washing machine. Pull the string towards the door hinge...
Thanks for your suggestion but there is only a small piece of cloth in there. I have cleaned out the filter so there is very little water and I have drained it again and again. The blasted door is still solidly shut.