Finally got around to making it. It's presently in the oven and the the house is filled with the fumes along with a loaf in the bread maker. Good combination. Cooking definitely innoculates against the nasty outside world.
I am coordinating a charity cook book at work as part of a little extra job I do and one teacher e mailed in his Xmas cake recipe. It included treacle and cocoa. Interesting. I put the zest of an orange and a lemon in instead of candied peel and forgo currants entirely in favour of sultanas and raisins. Oh and I soak the fruit in brandy before baking. Any variations that could be factored in? (Next year obviously...)