Both track controle arm bushes were knackered,i replaced them.On my mot failure list it says front brakes unballanced across axle,the brake pads are fairly recent.Would the knackered track controle arm bushes cause the unballanced brakes.

Afraid not, pull the pads and work the Pistons in the calipers until they move smoothly and while you are about it replace the brake fluid.

As above sticky piston, or calliper slider or pad seized in calliper and don't use WD40 near any of the rubber seals it may solve the problem in the short term but may well be what caused the problem in the first place.