After I got word of the bill I checked out the CEO list that Keasy posted and rattled an email off to the Director of Honda UK explaining the disappointment I felt.
Anyhoo, I heard nowt and didn't really expect to but they mailed me back earlier thanking me for my email and they've passed it along to their Customer Relations Dept who are investigating my concerns.
Nothing might come of it, but fingers crossed.

I had to re-read what I wrote in case I'd gone overboard, but it's not too bad. (I think I was still in shock tbh)
re: Feeling physically sick at cost of repair.
Dear David,
Approximately 18 months ago I purchased a 2nd hand Honda Accord 2.2 i-CTDi Ex and had a relatively trouble free experience until very recently when I began to experience intermittent drops in power accompanied by a flashing ECU light.
I felt that I'd be best served by having the diagnostic conducted at one of your dealerships (Parks Honda, Hamilton) and duly booked the car in.
Unfortunately (as is often the case with intermittent faults) they were unable to establish exactly where the problem lay, but cleared the log and the car was running fine.
While it was in, the service technician discoverd that the manifold was cracked and the cost of repair woul be approximately £900
..it's important to bear in mind that the current value of the car is in the region of £4500..
Luckily this was a known issue, the part was replaced under extended warranty and my estimation of Honda soared.
This was however very short lived after the power loss issue raised it's head again.
A few days after it was booked back in, the technicians were able to recreate the fault (the car actually broke down completely on a test drive) and the news was very bad indeed.
Their best endeavours concluded that they would have to replace the high pressure fuel pump and then re-test the car and the price I was quoted came as a hell of a shock I can tell you, but the real kick was still to come.
I had misheard the quote the girl had given me, and far from being the expected nine hundred pounds, it was actually nineteen hundred pounds (something I didn't discover until after the fact).
So the pump has been replaced and they've just been off the phone to say that they're moving onto replacing the fuel filter and I'm well over £2000 in bills so far.
And that is why I am currently feeling physically sick.
Taking everything into consideration.
For a (currently) six year old car that cost me just over £7000 eighteen months ago, has done less than 90,000 miles and would see me making a return of about £2000 after repairs (ergo a loss over 18 months of around £5000) I think it's fair to assume that Honda will be joining Nissan on my list of manufacturers (it's a short list, just Honda and Nissan) never to purchase from, or make recommendations for, again.
(Most members of the online communities I am involved with were shocked at the £900 bill, given the cars age, and I'm not relishing revealing that it's gone over £2000, because I'll look like an idiot who should have gone to a breakers for a spare, had it fitted on the cheap and got rid of the thing ASAP)