Forgive me, I fear that I have not explained myself well enough in my note as you seemed to have missed the point. (And apologies for the poor formatting of my note, I typed it in Word and then pasted it and the format has gone screwy and ommitted some of the words).

To reiterate, the point is that diesel boat owners are NOT getting a "concession" but are merely consuming fuel in accordance with the current UK law which is that red diesel (lower rate duty diesel) is available for "non road" use. Boats are "non road" and therefore benefit from the law. Ditto farmers, fork lift's, etc as per my earlier note.

I regret that I have no answer for your challenge as to why petrol boat owners cannot benefit from a similar arrangement - an answer would require a study of the law as to why "non road fuel" was classified as such and limited to diesel fuel only. I expect that the origin of this lies in the fact that non road fuel has typically been diesel and not petrol (there are no petrol tractors or fork lifts around!)

rob