Mmm,
On an office yo uare going to needa 60ft pole on I can understand the charge for the outside being a little higher.
the inside windows are also easy, single pane windows, that means they are an absolute doddle to clean.
It also sounds like most of the windows are going to be straight forward to get at.
The insides should stay pretty clean, offices are almost always smoke free, so you should not need a squeegee dripping with water, mopping up should be minimal.
At a £1.00 per window you are on easy street, that is a £1.00 per pane.
Unless I have misunderstood that is?
You said the windows were 3ft square?
If they are indeed only single panes, it is only going to take you 20 seconds per window.
Even allowing for a few awkward ones, most you will be walking up to without any hinderance.
If you are going to charge as much as £235 then you are going to have one hell of a good day!
The outside of an office that size is still only going to take you 3 hours, tops, and thats being really, really generous on time, 2 hours would sound more reasonable with WFP.
I'll lay odds that this is a job you will do inside and out in comfortably inside of a single day.
You can make serious money on this type of account with WFP, you'll get the outside done 4 or 5 times faster than you would with trad, though I do agree that you should charge the same as you would if done trad.
But the inside of a 4 storey office, providing access to the majority of the windows is straight forward, will be only a little slower than you would be on the outside.
Single pane windows are very easy and quick to do.
Best of luck with your price!
If you get the job, keep us informed as yto how long it takes you to get it done!
Ian