A leading healthcare think tank has called for "significant reform" to general practice in order to meet the challenges of NHS England's Five Year Forward View.
A report published by the Nuffield Trust found that general practice funding fell by almost £300 million between 2012/13 and 2013/14.
Increased resourcing and support will be needed to allow general practices to find new ways to meet patient need, the authors argue.
Most health and social care leaders (77%) agree that small GP practices are no longer fit for purpose, a separate survey has found.
And the structure of general practice does appear to be changing. Is General Practice in Crisis? found that the number of one-doctor practices has halved over seven years, from 1,717 in 2006 to 891 in 2013. The number of practices with more than ten doctors has grown by over 75%.
The think tank warned politicians seeking to reform general practice to avoid the temptation to adopt a 'one size fits all' model or top down targets.
Instead, local contracts and incentive schemes should be used to encourage solutions.
The GP contract should be used to encouraged practices to join with other healthcare professionals, such as hospital specialists, pharmacists, social care staff another other GPs.
Dr Chaand Nagpaul, chair of the BMA's GP committee said:“As the Nuffield Trust [write], GP services do not need more top down targets. While one response to these pressures is for practices to get bigger, or increasingly work together in groups, we must not lose the flexible and local approach delivered by many smaller practices that is so valued by many patients.
"Fundamentally, we need policy makers to properly support and invest in general practice so that it has the ability to deliver the care that patients deserve.”
Nigel Edwards, chief executive of the Nuffield Trust said: "There is no doubt that general practice is facing great pressures at the moment. Funding is tight, there is an impending workforce crisis - and perhaps most significantly of all - the needs of patients have changed beyond recognition, as the population lives longer with chronic conditions.
"As our panel of health and social care leaders recognise, the single-doctor practice is now struggling to deal with these challenges and is looking increasingly unviable. But more money alone isn't the answer."