Millions face a postcode lottery in GP services as chronic underfunding has left doctors surgeries' "on the brink of collapse", a top medic has warned.
Research carried out by the Royal College of General Practitioners (RCGP) showed a stark divide in access to doctors, with people living in the most deprived communities facing the longest waiting times.
The study found that 22% of people in Bradford raised concerns about not being able to make an appointment with their GP. Whereas the figure was just 5% in Bath and north-east Somerset.
There are "shocking discrepancies" in the number of GPs employed locally, the RCGP warned. North, east and west Devon have 60 GPs for every 100,000 patients - three times as many as Slough in Berkshire which has just 22.
The poorest appear to be the hardest hit by this patchwork of provision, with e ight of out of ten areas with the longest GP waiting times having moderate to high levels of deprivation.
The College said the research, based on the GP Patient Survey, showed the profession is " creaking under the weight of a growing and ageing population".
They have launched a campaign to demand an extra £3.5 billion a year to be ploughed into GP services, and have put up posters in surgeries showing patients having to queue down the street for an appointment unless extra cash is found.
Dr Maureen Baker, chairwoman of the RCGP said: "Every single patient should be able to see their GP when they are in need of medical assistance, regardless of where they live.
"It is absolutely shocking that, due to the current funding crisis in general practice, patients are now facing a postcode lottery.
"It is doubly unacceptable that those patients affected tend to be those who live in deprived parts of the country."
A growing and ageing population coupled with a surge in patients with multiple and chronic conditions was piling pressure on GPs, but their share of the NHS budget has been slashed, she said.
Dr Baker said: "Family doctors are working harder than ever - but with increasing patient demand, due to a growing and ageing population, and plummeting investment, there simply aren't enough GPs to go round.
"There is now a desperate shortage of GPs in many parts of the country, leaving the service teetering on the brink of collapse.
She added: "Over the last decade, investment in general practice has slumped and has now reached an all-time low, with GPs conducting 90% of NHS patient contacts for just 8.5% of the total NHS budget.
"GPs want to provide high-quality care for every single patient, but at a time of plummeting resources we are seeing 40 million more patients a year than just five years ago.
"The simple fact is that family doctors are now heaving under unsustainable workloads, with the majority now routinely conducting 60 patient consultations in a single day."
The College said the number of visits to GPs has soared from an estimated 300m to 340m in the past five years, and a t least 10,000 more GPs need to be recruited to ease the pressure.
Dr Patricia Wilkie, president of the National Association for Patient Participation said: "Patients across the country are frequently unable to obtain a timely appointment with a GP, because there simply aren't enough GPs in some local areas.
"This postcode lottery is totally inappropriate with clear and potentially serious implications for patients.
"It is clear that the root of the problem is a shortage of GPs and the lack of funding for general practice. Without appropriate funding for general practice the situation for patients will only deteriorate."
NHS England said they are recruiting and training more GPs. A spokeswoman said: "Patients should have good access to health services, regardless of where they live.
"This year, for the first time, NHS England introduced a deprivation factor into local health budgets to start to redress historic funding issues."