Rear brakes

My van failed it's MOT test on the rear brakes being out of balance the nearside being the least efficient.
I replaced the wheel cylinder and flexible hose on the nearside and bled the brakes, took it back for retest no difference. Tester suggested replacing brake shoes, so even though the shoes were only 3 years old and done less than 2000 miles I replaced then and took it back to the mot tester. Still not much difference in the efficiency but the hand brake was perfectly balanced which suggests to me it could be hydraulics but I am open to any ideas people may have.

The rear brakes are split from a T connector on top of/near the gearbox. Brass looking thing. Follow the brake pipe from that T-piece to the cylinder and check for damage. After that take a pic of the brake internals to show us, and if nobody can spot your issue then check the runout/condition of your drums (needs a machine shop, but I'm just thinking that if they're warped, you'll be backing your shoes off further than on the other side)

I have replaced the wheel cylinder with a new one and that made no difference.
Taking a photo of the internals is a good idea I will try to do that this weekend.