Hi Everyone
I tried a mild body fat remover - Didn't work - I tried also tried a blood and protein remover - Didn't work. I also tried (in a small test area) white spirits - Still didn't work.
Contacted the club treasurer, explained everything, I also informed him, that someone has previously tried to remove this with a scraper and has scratched all the Perspex (not me). I think that’s why he got shot of the last window cleaners.
Anyway, I have advised him to get new windows fitted and then we will be able to keep them clean :-)
Thanks for everyone’s help anyway
Andrew