£1,400 for a bedsit?! It's very luxurious compared with the bedsits that some of my friends lived in, in the '70s, but even so that price is shocking!
Perhaps it's because people want higher standards nowadays. In the '70s, my friends' bedsits didn't have central heating and had no bathrooms or kitchens - in those days kitchen and bathroom facilities were shared with other tenants in the building and the heating was either a plug-in radiator or maybe an ancient (and useless and probably dangerous) gas fire.
However, in the '70s bedsits were cheap, probably about £12 a week rent. Bethnal Green would have been even cheaper, as it was a very downmarket area, as were many other parts of London that have since become fashionable (e.g. Islington, Holloway, Crouch End, Hornsey, Notting Hill, Camden and the like would all have been as cheap as chips because nobody particularly wanted to live there).
Prices started getting silly in the 1990s. A family member was living in London about 20 years ago and lived in a single room in a shared house, where the kitchen and bathroom were shared between 4 people. Their share of the rent was £800 a month. I dread to think what it might be now!