We do not have estimates of the number of households in each local authority area in London which have a right to buy. However, an approximation of this can be observed from related statistics.
Table 100 available at:
http://www.communities.gov.uk/housing/housingresearch/housingstatistics/housingstatisticsby/stockincludingvacants/livetables/ shows the dwelling stock by tenure in each local authority district. Tenants of occupied local authority owned properties who have been in social housing for five years or more are entitled to right to buy.
Estimates of the number of tenants entitled to right to buy in each local authority area are not available. However, the English Housing Survey provides an estimate of the length of current residency for tenants at a regional level. This shows that in 2009-10 around 300,000 households in local authority owned stock in London had been in their current accommodation for five or more years. However, this does not capture those that have previously been resident in social housing prior to their current accommodation and therefore is likely to be an underestimate of the proportion that are eligible for right to buy.
Furthermore, some tenants living in housing association stock from pre-1989 will also have the right to buy and also some tenants living in housing association stock which has been transferred from local authorities have the preserved right to buy.