Partial success!

After suggestions from this list, I found a mild abrasive window cleaner called "Glass Science, Glass Scrub, Cream Cleanser". The paste has the appearance and smell of toothpaste.

After much scrubbing, the windshield has improved. I must have been wrong in thinking that the cloudiness was inside the glass. I have not been able to completely remove the cloudiness but I'm pretty sure some more scrubbing will remove it.

Thanks list.

Will Mayall