Seriously though what I call heritage leaded glass (proper leaded windows with individual panes of wafer thin brittle glass held in place by lead) is a very high risk job so good luck with that one.
I had a contract with a company, and the lady who owned it would have us do her house on request really.
Every window was how u described it smurf. First time I done it I thought the whole window was going to fall out.
We used a piece of cardboard cut to size of window, a lad would go in and hold it up against the windows as the outsides was cleaned, using wet and dry unger microfibers.
House must of been built in the dinosaur era but was very nice indeed