Best question of the week comes from Erin, who asked me to explain espresso powder, which I used in the coffee and walnut cake below.
Espresso powder is not coffee grounds, but like instant, freeze-dried coffee - Nescafe, Gold Blend or whatever - but it's only for making espresso. YOU CAN GET IT IN WAITROSE but you have to look quite hard. The tin I've got was, I think, the only kind they sell in WR, it's called Percol Espresso and you can find it in amongst all the other instant coffee stuff.
(Sorry no photo but my camera keeps flashing an "ERR" sign at me and refusing to take pictures.)
Alternatively, if you have any kind of espresso machine, you can make up any quantity of espresso needed in a recipe (usually a cake, but Nigella does some wacky Breakfast Banana Smoothie thing that requires it aswell) using your machine.
We have an espresso machine but as you've all guessed, it's sitting in the cupboard under the counter top occupying the space left by the deep-fat fryer (cellar).