It may look like an error in the question, but it is actually highlighting an error by the cyclist. It happens regularly close to my home where there are two left hand turns very close together- the first a residential cul-de-sac and the next a cut-through lane. Most cyclists want the second one, but indicate before the first one.
I was brought up with a - perhaps unofficial - "always signal in good time" which I have since learned to modify. Driving (yes, I can) home from Melksham Town Centre (yes, it has one!) there is in quick succession
- a right turn into Warwick Crescent
- a left turn into Coronation Road and then
- a right turn into our driveway.
If there was no Warwick Crescent, I would be signalling right in good time to alert traffic behind me ... however I have learned that doing do misleads cars emerging from Coronation Road who will start out from there thinking I am turning; approaching the whole junction layout slowly is perhaps irritating to people behind me, but then they are already slowed down for my right signal as early as I realistically can, but still unusually late.
I do have a high-Vis vest on the coatrack in the hall, rapidly grabbed each time we hear a bump on the road outside / at that corner. Usually slow speed stuff, but a corner to treat with care!