Unlike the older (pre 97?) Minis equipped with the 4-fuse verdegris trap under the bonnet, MPi Minis
have proper modern fuse holders mounted inside the car.
This does mean that there is a different technique when adding extra wires to take fused feeds off the box:
undo the four screws on the corners of the fuse block
roll it to the left (looking forward).
the back of the block is exposed and it's a doddle to
pick out a wire and put one of those doesn't-break-the-wire in-line taps on the
circuit of your choice