RRC Vogue LSE rear view mirror

Hi. I've joined hoping to talk to other enthusiasts and to get a bit of help from time to time with my RRC Vogue LSE, which my son and I have just had the bodywork restored on and it looks superb. I need to replace the photochromatic rear view mirror. I have a new one to install, but not sure how to take the old one out. I've removed the screw and unplugged the wires, but I can't slide it out and don't want to force anything in case I damage anything. I've looked on the web and can only find P38 mirror replacement advice. Can anyone help a newby?

Cheers

David