Tony,
I remember recently reading an article in the papers about a restaraunt reviewer.
This guy eats in posh restaraunts, then writes about it, and a magazine pays him for his written articles.
Now is the food he eats in the restaraunt an expense?
Well, the food writer reckoned it was, so did his accountant; so it was submitted as an expense.
Subsequently he was investigated and the tax man decided that because the food he ate had a dual purpose (you have to eat to live), he couldn't claim it as an expense.
So in this instance the accountant was wrong! I think when it comes to the 'nitty gritty' of certain stuff, there's no clear right or wrong; but what you can justify using your common sense.
I'll take a trip down to the libarary and the facts on Capital Expenses and how they apply to window cleaners; I'll do this next Monday.
Oh, and I reckon your accountant is wrong with regards to purchasing work from other window cleaners; that's got to be an legitimate expense!