I have a warning on my S2 concerning the rear brake ABS sensors when it went in for it's last service. It might be a similar issue, listen for a road speed related click/ping noise from the rear axle if it is this.

On the rear drive shafts the sensor rings have small lobes which go past the sensor to give the pulses it uses to measure the rotation. These rings are a tight fit over the drive shaft near the wheel hub. The issue is with the ring expanding or working lose over time and so the lobes clip the sensor. You hear a click/ring sound which changes with road speed from the back of the car.

Apparently these are the same as BMW 1 Series and it is a common problem on those cars. Fixing it will be a fairly simple job, either new drive shaft or if they are interested in manual labour then they can swap new rings onto the existing shafts.

If this has been happening for some time the sensor can become misaligned and generate an error. The engineer told me to get them swapped soon. Since then I have not even been able to use the car so that's a pain waiting to get fixed along with the rose joints on the rear suspension.

Everyone loves a Morgan. Even me, unless it's broken again.