On a hot morning back in May, having taken the train down to Kidbrooke Village in south-east London, I leant over a balcony, halfway up the 21-storey Birch House as I waited for my turn to interview the mayor of London. 

Looking out over a sea of crouched brick buildings from this high-rise island of densification, it was clear that the choice of location for Sadiq Khan’s big announcement that day was no accident. Density – including in previously untouched bits of green belt – was the name of the game in the housing strategy he was launching, and underpinning it all were transit links, new and existing.