Apparently its all one cable from left to right. Presumably you only need to adjust on one side but obviously best on both sides. Saying that my handbrake cable is seized and I am awaiting the fitting of a new one under warranty. Make sure whole cable is well oiled/greased. The mechanic said he would soak my new cable in oil before fitting!
PS my handbrake has never really worked from new and I am sure it would fail an MOT.
