Ok, further to this
http://www.cleanitup.co.uk/smf/index.php?topic=90943.0#msg811579, I got the contract and did the first clean this week. It wasn't too bad, and we got everything done in a day and a half, which considering the state of a lot of the glass was good going.

I do have a question and would like the advice of those who regularly work at heights of 45-55':
What brush do you use? We were loaned a brush that proved to be a bit of a handful and not particularly user-friendly. It was probably 4-sections of about 12-14' a section, and was therefore awkward to put up and adjust, and hellish to control as it was super-flexy. In the picture above you can see the balconies which we had to clean, unfortunately the metal railings are on the outside so the brush had to be lifted in to each section, which was super tough. So we're looking for a new brush that will be stiff, easily adjustable and light. For the money, I can't see anything that comes close to the Gardiner Superlight SL-51, but how stiff is it and how easy is it to adjust the height? Any other suggestions? It's only going to be used once or twice a month I should think so cost-to-use is a factor...