And I said to Timmy that my wheelchair was making a noise, he went into the bedroom and fetched it, when I sat in it and moved he could hear it, he looked closely and said "That nut, holding the wheel on, is just finger tight", tightened it up and it seems silent once more.
It is still a bit noisy at lunchtime(1) but not half as noisy as it was before, there is another enormous nut which he will bring a bigger spanner for on monday....
(1) When I am using it as I am so exhausted after gym...