Following on from JammedStab's comments regarding putting fuel in the watermeth tanks, I know of one incident in XS606 of putting demineralised water in one of the water meth tanks (demin water was used by Harriers that were operated from the same base). On a short take-off from a grass strip the crew had full wet power until just after unstick at which point the watermeth that was in the lines to one engine ran out and demin water was injected into the engines resulting in a serious loss of thrust. Luckily, they were light weight and flew away safely. I am not speculating that this could have happened in this accident because the incident to which I refer was caused by a local procedure of keeping water meth in barrels with demin water labels on (don't ask!).
The last flight of this aircraft as XS606 was on 19 December 2012, 20 minutes from Boscombe Down to Bournemouth. Many happy hours in it.