[anyuser]

Should I be concerned about this as the limit for MOT pass is now 58% and yesterday's MOT is showing 59%?

[Ennoch]

How corroded are your discs? My brakes on the estate were garbage and really not confidence inspiring but now I've had a chance to drive the car more, and more aggressively, they've cleaned up and are actually pretty damn good. The brake efficiency is calculated based on total vehicle mass/effort*100 so a rather arbitrary calculation (although necessary) as it doesn't take into account the brakes are cold (some pads prefer to be warm), or the aforementioned rust etc. If they didn't flag the performance or the brake condition as an advisory then I wouldn't worry too much, especially if you're otherwise happy with how the brakes feel.

[anyuser]

Thanks, they didnt flag an advisory so, as you say, I probably should drive a bit more. The disks look good currently so I am not worried about how they look or work but only 1% above the limit was a concern.

[Revoltos]

The "service brake" is that the hand brake? If it is, the part of the disc you can see on the rear that the caliper straddles has nothing to do with it. The hand brake is using brake shoes on an inner bore on the inside of the disc. It is adjusted by a ratchet adjuster that you access through one of the wheel stud bolt holes.
You can help "improve" the performance of the hand brake by ensuring it is correctly adjusted and when safe to do so, apply the handbrake whilst driving at a moderate speed. Dont worry, there is zero chance it will lock your back wheels.

[Ennoch]

Originally Posted by Revoltos

The "service brake" is that the hand brake?

I thought that too, but no, that has its own entry called 'parking brake'.

[Harryg]

I may be wrong but does the star symbol mean the brakes locked out as I see the rear parking does not have one on the o/s. So wheel never locked

If the brakes lock out it is showing that by the star next to it so brake performance is met because it has locked out at 59% so your service brake (footbrake) is excellent as the rollers cannot read higher once the wheel is locked.
I would be worried if no stars were showing as that means at the 59% showing that is the brake force pressing the pedal hard not locking and wheel still moving.

Service brake is the footbrake and secondary brake the handbrake.

[anyuser]

Thanks for all the advice. I will not be worrying any more!