Thanks to JF for enlightening on the subject of ground loops and the reasons why.
I recall landing [as a student] at Southend on a greasy runway [before they redid the friction course a few years ago] and noticing the right wheel brake disc momentarily "snatch" during touchdown. This was very odd as the a/c did not have toe brakes and I hadn't accidentally touched one.
Anyway the resulting weaving down the runway must have been hilarious for onlookers - it certainly got my attention!
I now realise that I was very lucky to be in a tricycle aeroplane that tends more towards forgiveness.