S_pugh, I agree with you about the double unches, which are unfortunately becoming increasingly common in the Listener. Until a couple of years ago they were hardly aver seen. I don't mind the grid ambiguities since they are resolved by the theme.
As you say, the puzzle is a generally good one - enjoyable theme and excellent clues, but the double unches and the asymmetry of the legs suggest to me that the setter has not battled all the way to get a totally satisfactory grid. The contestant in the 'race' looks as though he's been subjected to torture and had a leg broken, poor chap. Out of interest I tried to see if a better depiction were possible using the two abbreviations, which are of equal length, for the legs, and the shortest other obstacle for the bracing strut. It didn't take long to achieve a satisfactory grid and perfect depiction by swapping the upper and lower obstacles and re-structuring the barring.