We are told it is.Only, as you know, if it's a ring final.
We are told it is a ring final, on a 32A MCB, and it is supplying sockets.
How strongly do you wish to assert the possibility that it is not wired using 2.5mm²
As for the spur, we know that most of it probably has a CCC of 32A, and your just guessing about the last few inches/feet.
Spur or not is irrelevant.
How many times do I have to keep saying that?What the spur is wired in is of no relevance whatsoever.