Rear suspension

The rear suspension on the driver’s side on my car has become very firm – you feel it when you drive the car.

With the car parked if you bounce the corners as you would to check the dampers, the other three corners push down as you expect and spring back, but the rear driver’s side has to be pushed much harder and won’t go down nearly as far.
I have checked the static ride height and it is the same on both sides
I was wondering if that one damper has partially seized?

Any suggestions much appreciated

Certainly sounds like a problem with the damper. To double check remove the damper and try to move the suspension arm up and down by placing a trolley jack underneath to rule out seized pivot bushes You'll obviously have to support the body on that corner while you do it.

I had a similar problem with my Fiat Coupe.
It turned out to be the pivot where the lower end of the damper was mounted to the suspension arm was seized solid I never managed to withdraw the bolt, had to cut it off then remove the suspension arm and drill out the remains of the bolt.

I hope you don't have that much fun sorting out your problem.