Supply staff are covering an estimated 10 per cent - roughly 4,000 - teaching posts in London daily. This figure frequently rises to 6,000.
More than two-thirds of the staff supplied by TimePlan, Britain's largest teaching supply agency, now work in London schools and it claims pupils can have up to 12 teachers for one subject in a year.
A survey carried out by the Teacher Training Agency, with information supplied by recruitment strategy managers in London, predicted 1,664 vacancies in primary and secondary schools in the capital in September.
The figure includes posts covered by supply teachers. The Department for Education and Employment estimated there were 430 vacancies in London secondaries at the start of the academic year.
A survey by The TES and the Secondary Heads Association meanwhileclaimed vacancy rate nationally in secondary schools at the start of the new school year could be as high as 4,000.
Shortages are exacerbated by the high housing and travel costs and difficulties with schools under special measures or with serious weaknesses.
The latest regional house price analysis from the Nationwide Building Society shows that average cost of a home in inner London is between pound;132,500 to pound;145,000 - way beyond the means of many teachers.
The Association of London Government will next week meet education minister Estelle Morris to request mortgage assistance for teachers in the capital.
It suggested giving councils or housing associations money to enable them to provide accommodation for skill-shortage areas.
The ALG also recommends that teachers become one of the main beneficiaries of any nationwide Home Starters Initiative proposed by the Government.
World teaching shortage, 12