AS Roger said, microfibre and a good window cleaning spray, both of us would highly recommend tesco's own brand, it's cheap and very effective.
I know Rog thinks he is as quick or quicker on these with spray & buff as he is with a squeegee on a normal window of the same size...but he wouldn't dream of using spray & buff on them instead of applicator and squeegee!!
On real leaded, and not the normal modern stuff, if you use WFP then you have to be wary of leaks, loose panes, broken panes and so on, but it's better by a vast degree than anything you can do trad providing that is that the windows are in good repair.
If you are staying trad then stick with spray and buff on leaded, how much to charge?
Well you have to charge more per window than you would for non leaded windows, if it would be a tenner for standard windows, then it should be at least £15.00 for leaded...minimum, at least half again as much.
Customer doesnt like it?
tell them it takes more than twice as long, and on no account drop your price, get it set in your head that you are not going to lower your price.
If you do, then you will only find yourself dropping the account (as others will have probably done so before you)
On leaded (no matter what Squeaks may think) WFP will give better results, spray and buff WILL leave smears, but because they are leaded, the lead strips deceive the eye.
Once you are experienced with WFP there is no reason why you shouldn't do a top job from the very first clean, if you are new to WFP then it can take a few cleans to get it right, and when you get it wrong with WFP you can REALLY get it wrong
On leaded, with WFP you will be 2 to 3 times quicker, if you price the same way you would for trad then you can clean up
(pun intended)
But because you are so much quicker, it is hard to price it higher than you would for the same house with non leaded windows.
Even more so with georgian windows.
Done trad, leaded is just harder work spraying and buffing than applicator and squeegee and can be done quite quickly, georgian on the other hand is a different kettle of fish.
Trad can't get remoely close to WFP on these, you are at least 5 or 6 times faster with WFP, and providing frames are in good condition you will do a better job AND the frames will be cleaned too.
If you are new to window cleaning, stick with trad until you have built up a full round and have fully developed your trad skills before you consider going WFP though, it pays of in the end and you will have developed enough window cleaning wisdom to cope with any problems that occur.
Ian