[notahacker]

> But the price jump from one bed to two bed was much larger than any of the other jumps.

That price jump isn't particularly surprising given London's one bed flats are competing against a vast number of individual rooms in shared properties rented out (which is regarded as a normal living arrangement in London, including for professionals, somewhat older people and to an extent couples). Obviously people who need an extra bedroom aren't really in that market, and the second bedroom is also easily [sub]let out separately.