Well folks, my resolve weakened and God damn how easy it is to buy things on the wife's Amazon prime account. I blew sixty five quid on a 'Blucky' cordless pressure washer from Amazon.
I had looked at the Worx and the Ryobi etc. and tried to find reviews and, to be honest, the reviews were no better than for the cheap Rinky Dinky one's and, given that the Worx one's start at something like a hundred and sixty bucks I decided to take a pop on a cheapo. Well it arrived this evening with two fully charged four amphour batteries. I filled a bucket with water and went outside and was pleasantly surprised to discovered that it easily blasted years of moss away from the window sill of my living room window and it had no problem hitting the upstairs windows of my house although the soap sprayer attachment wasn't as effective at height. I dragged the Daytona out and filled another couple of buckets and then hosed her down with Carp plan wash'n'wax that I bought alongside the machine for five bucks and it did the job just fine without even running down the first battery.
All in all I'm rather pleasantly surprised as I was expecting that it'd be little better than my pump pressurised garden sprayer if at all but it is fairly powerful it seems although it won't rip the paint off by any stretch and I particularly chose this one because the pressure varies depending on how much you squeeze the trigger where the others, from what I could tell online, either just had a couple of settings or were simply on and off. The only thing I'd criticise with it is the vinyl hose that comes with it which is easily crushed cutting off the flow to the unit. I'll pick up a length of more rigid hose at some point to replace that and I will maybe source a couple of large plastic cans for water as you can go through bucketfulls quite quickly.