So this morning I composed a nice email to Company B telling them I was exploring other options and could I have a few days grace to make my decision. Before I had a chance to go back to Company A, I received a formal offer from them! It looks very much like I will be in a new job on the 2nd of January!

Thanks for all the advice yesterday - It really does help to get a different and objective viewpoint!

Lots of excitement about the new job (not least of which is that I am going to have to do some shopping and up my work wardrobe a bit - my MOTG outfits may not cut it in the new company!)