Hi everyone,
just returning to an earlier topic.
I decide to take the job on and have attached a photo of the end result.
Whilst appreciating your helpful suggestions, I decided to use a well tried and tested chemical that I knew wouldn't damage the glass or rubber seals on the conservatory, and it's very very cheap........
White Vinegar !!
Well it did the job really easily, the customer was very pleased and therefore so was I.
Just mentioning it in case it can be of use to someone else in the future.
Les