Today’s main lesson is that Mill Hill is a real place, not just a trap disguised as an unlikely branch of the northern line.

Mill Hill Broadway station is one of the least beautiful in London. Its entrance is beneath the M1 motorway, whereas the similarly grim Hendon station sits alongside it.

I was in Mill Hill in order to cycle through the rain to Arch North, for some afternoon bouldering and the promise of dim sum down the old Watling Road.