No, it is not the mean average, it is the median. You are quoting the wrong statistics - you are including part-timers, but he is talking of the median full-time earnings, which are actually 27.2k on average nationwide according to the ASHE. The median full-time salary in Greater London is 32.8k, and still 29.9k in the outer South East.
Of course your broader point still stands - in London you can only own a house if you earn in the top deciles, or if you inherit a house or get gifted a deposit by parents/grandparents who got lucky in the house price boom. The latter is the default way.
Of course your broader point still stands - in London you can only own a house if you earn in the top deciles, or if you inherit a house or get gifted a deposit by parents/grandparents who got lucky in the house price boom. The latter is the default way.