Thanks for the reply, Amelia. I did end up with a recipe from Good food. I don't think it would suit you though, as I prefer a set cheesecake to a baked one. My Dsis makes a baked one from an Annabel Karmel recipe that everyone raves about, but I don't like it so that made my mind up.
I made one that used a packet of choc digestives and 100g butter for the base. Even a day after, it is still crisp. Yum.
The topping was 3 x 200g tubs of plain philly, a few ounces of icing sugar, 300ml double cream, 100g grated choc and 2 tablespoons of Baileys.
Whip it up. Fold it in. Chill. Kept some of the chocolate for the top and it looks pretty too.
I stuck to the recipe rigidly. It made 12 healthy slices. Next time, if we fancy a decadent desert I shall use a third of all the ingredients and make a smaller, shallower one in a 7inch sandwich tin, rather than a deep 11 inch springform tin. That will give everyone one serving but two for me as DH hates puddings and really hates Baileys what a shame 
We've enjoyed eating it for 2 puddings though and I know that quantity is good for making it for dinner parties.
Off for my final slice.