Thanks it's a Hudson reed one. Apparently they no longer make the cartridge for it. Was a strange design. It turns the water off and also diverts from the shower head to the shower riser.
Thanks so if I take of the control knob off for the one that moves the temperature up and down. There maybe a way to adjust it so can move/turn it hotter?
The over height is 140mm from the bottom of the tank. So is quiet low. It's usually recommended the cold hight of the cistern is 75mm below the overflow flow height?
Can you swap a part 1 float valve for a part 2. By splitting the valve. And just changing head. So leaving the body of the valve in the tank, connected to the tank connector?