Thank you Charles. I followed your 'How to open the Normal Template..." link and followed the instructions so that Word opens with my customisations intact except for the page colour. It seems that Word can only open with a white 'Page Color' which is annoying (I find it too dazzling) but I suppose I will have to accept that's how it is and use a workaround.

I have put a shortcut on my desktop that points to another .dotm Word template in my 'Custom Office Templates' folder and this opens as I want with the customised page colour so it is an acceptable workaround.