Evidence suggests that the vast majority of GPs aged over 55 plan to quit the profession within five years - leaving some CCGs at imminent risk of severe workforce shortages.
GPonline has mapped data from NHS Digital to reveal the parts of England most at risk from the impact of an ageing GP workforce - click on the interactive map below to find out how your area compares.
A total of 16 of England's 191 CCGs have more than a third of their fully-qualified, FTE GP workforce aged 55 or over - and a further five are within a percentage point of this mark, our analysis shows.
Nearly half of CCGs have more than a quarter of their FTE GP workforce in the 55 or over age group, and in five of England's 191 CCGs, 40% or more of the FTE GP workforce is aged 55 or older.
GPonline revealed last month that the NHS' reliance on GPs aged over 55 had increased sharply over the past three years.
And a huge BMA poll in 2015 - which received responses from more than 15,000 GPs - found that around 80% of those aged 55 or over planned to retire within five years.
Meanwhile, the RCGP warned last year that 2.5m patients in England could see their practice close within the next five years because most of their doctors were close to retirement age.
Although numbers of GP training places are at record levels, the GP workforce remains in decline - with a loss of 441 fully-qualified FTE GPs over the year to March 2019.
BMA GP committee executive team member Dr Krishna Kasaraneni told GPonline earlier this year that general practice needed to see a sustained rise in fully-qualified GP numbers - and in the wider primary care workforce - to ease pressure.
'GPs aren't leaving because they want to - but because the workload is out of control,' he warned. 'The only way to fix that is to increase the wider team, and improve GP recruitment and retention.'
NHS and GP leaders are hopeful that the launch of primary care networks, which went live across England from this week, can begin to ease pressure on GPs by recruiting thousands of pharmacists, physios and other staff to support primary care.
But heavy workload in general practice and punitive pension taxes that have forced many doctors to reduce their working hours or retire early continue to undermine the GP workforce.