SAGA are my insurers and I had a replacement screen a few months back.
When calling SAGA's windscreen hotline I was transferred automatically to Nationwide Windscreens the recommended installers. They had to rearrange my fitting appointment 3 times as the screen wasn't delivered to their depot in time.
Speaking with the (reassuringly mature) fitter he said he's only done a couple RC screens and they always have delays on the delivery as they have to come from Lexus. Obviously Lexus do not make the screens (he thought it was Asahi ? ) but the screen is all marked up just as the original one was.
The chap took his time and did a great job!