Please advise the best way to install new windscreens in my XK140 fixed head coupe. I have the correct size flat panes of glass and the correct rubber surround but there must be a special technique. Any suggestions?

 

The spares drawing shows a single seal for the two panes of glass. I'm not sure how a screen fitter would do it, but probably fit the two panes into the seal, then wrap a long piece of string all around the outer "slot", then offer the assembly up to the car. A helper keeps the assembly pressed onto the screen aperture, then with you inside the car, you pull gently on each end of the string to bring the lip of the seal over and into the inside of the windscreen aperture. Using string means no prospect of damage to paintwork. Finally, you seal the screen with sealer sold for that purpose. Heres a "how-to" off the internet: -

https://www.thoughtco.com/install-wi...g-trick-281410

Last one I did was the front screen on a Mark 2. These are a bit different, as they have a separate filler piece to put in once the main seal is in place.