Electric Shower Problem

My electric shower stopped working... One minute I was lathering up nicely, then "bang", off it went.

Diagnosis resulted in some very strange electrical readings and a mistaken replacement "on/flow" valve. Further investigation (well, taking a good break, then re-assessing the wiring with "fresh eyes"), highlighted the fact that the feed cable from the isolator switch into the loft-space, was not the same colour as the feed coming through the wall to the shower unit. Here's what I found...

Holy crap that's dodgy!

Talk about cowboy workmanship - YEEE HHHHAAAA!!!