Woodman,
I would be very happy never to beat that !!
About 30 years ago I did clean a very dirty set of theatre curtains and what a mess it made to my schedule for the next fortnight.
First problem was the scaffolders turning up a day late and that was just the begining.
One tip you may find of use:
The first thing to tackle once you get to the clean is obviously the cobwebs/dust/dead insects etc, and here I found the best approach was to use a powerful tub vacuum attatched to an electricaly powered carpet brush, something like a Victor D9 setup, with the lower swivel taped in to give a suitable working angle.
Not only will this give a wide path but the extension tubes give you a long stroke and you should find it more effective against nicotine-laded cobwebs.
After the innitial dry vacuum it may be worth attacking at least the upper areas with an old-fashoned carpet beater before moving down.
One thing I would most certainly do is, after arriving at a quotation price, add a further 25% to cover the unforseen and either make the job realy worthwhile or price myself out of the running
