Handbrake adjustment discs?

[DMC]

Hi

My car failed its yearly inspection on the handbrake not holding enough on the driver side.
It only just failed by a few percent from passing so the reading was very close!

My car has had quite a lot of work over the last few years the handbrake cables and calipers all look very fresh. Its got a disc rear axle.

Im not quite sure where to start with this. What could I check or adjust slightly?

Thanks!