Get on Roger!
You won't do that house in under 15 minutes, allowing 2 moves of the ladder for the upstairs bay windows that is 18 windows, I know you would probably walkl along the roof to get at those two at the front, but those tiles can be very tricky to walk along, and would slow you down a little.
Only two panes per window I know, so quick and easy to clean trad, but even so.....18 windows in 15 minutes or under??
Don't think so.
I'd be more expensive than both Tosh and Squeaks, £12 to £15 for me, though £15 would be the top end and it would have to be in the right area.
At £12 I'd expect to get and keep this house wherever it was in town.
Mind you...if it was rural then it would be £15 to £20.
Most will do this place in 25 minutes or so, however you approach it, that sloping roof will add a couple of minutes to your time.
20 minutes will be easily acheivable though.
Ian