In leafy South West London SHA there were 504 women GPs compared with 455 men in 2005, NHS workforce statistics show.
Women now make up 53 per cent of the GP workforce in Richmond and Kingston.
In North Central and North West London, women are also set to knock men off the top.
GPC member Dr Gillian Braunold, a North West London GP, put the shift down to changes in medical school output and to women GPs' partners being tied to London for work.
Nationally, women constitute 40 per cent of the GP workforce.
The headcount figures exclude locums, registrars and retainers, so the total number of women is likely to be higher.
The dominance of women will give workforce planners headaches. In South West London, more than three quarters of the GPs working part-time are women.
A spokesman for South West London SHA said:'This does have implications for workforce planning and training. The Workforce Review Team will be keeping a very close eye on the demographics.'
Nationally, women are more than four times as likely to work part-time as men.
However, GPC member Dr Fay Wilson said that the growing number of women in general practice is still not being replicated in levels of leadership, citing a 'very combative and masculine environment' at the BMA and the 'old boy culture' in some LMCs.
She fears that the lack of female perspective might also have skewed the new GMS contract in favour of men.
'Partnerships are now more highly sought after and difficult to get,' she said. 'Women might be less likely to seek one if they have to be geographically mobile or to get a partnership if they need to work on a limited commitment because of families.'