I drove past the car park behind the Theatre Royal as I do 4 times daily minimum and just could not bear the usual sight any longer and hope by posting on tripadvisor other people will avoiding using the car park ( the locals certainly do ).
The car park is privately owned ( no sign that says it's actual name) and is directly opposite the back door of the Theatre.
Every single time/day I drive by I see cars clamped by overstaying the time and the release fee is horrendous. This morning I saw a young swedish family with little kids being the victims and it is mostly tourists/out of towners being hit. It does create such a bad impression of Windsor, especially at there are so many decent car parks around and ALL of them cheaper too.
How this company gets away with it is a mystery and can not believe the council gets nothing done about it.
Anyway AVOID at all costs, the car park across the street behind Brown restaurant/public toilets is perfectly ok and does NOT clamp and there are others in the area ( Alexandra Garden, King Edward Shopping Centre, Vicoria Street are some of them)
Avoid the Thames Avenue car park like the plague if you want to have an enjoyable time in Windsor.