More than 20,000 people waited four hours or more in A&E at the St George's University Hospitals Trust last year, according to NHS England.

The trust's major A&E department is performing badly against the NHS national standard for waiting times in A&E.

The NHS target is for 95% of people visiting A&E to be discharged, transferred or admitted to a ward within four hours of arriving.

At the St George's University Hospitals Trust that figure was 86%.

The 2017-18 report shows that the trust's major A&E department saw the equivalent of 427 people a day last year.

Around 155,900 people went to A&E, up from 153,500 the previous year.

Of these, 21,359 waited for more than four hours, from arriving in A&E to being discharged, transferred or admitted to a ward.

Dr Chris Moulton, vice president of the Royal College of Emergency Medicine, said that the pressure on A&E has "spiralled out of control".

"If you keep stretching an elastic band, eventually it will snap," he said. "You don't ask 'why did the elastic band snap' - it snapped because you stretched it."

He said that A&E departments were struggling to cope with the demands of a growing and ageing population, particularly since a lack of social care beds keeps elderly patients waiting in A&E.

He said that the more "badly stretched and understaffed" departments there were, the more difficult it is to recruit junior doctors, creating a "vicious circle" of staff shortages.

Dr Moulton still supports the 95% target, saying that it's a "good pressure" on emergency departments to keep as few patients waiting as possible."

According to Dr Moulton, the solution is simple - more acute hospital beds, increased capacity in social care, and the staff and facilities to keep those beds open.

He said: "It's not a magic formula. It's a blindingly obvious solution."

Independent health charity, the King's Fund, said that A&E performance is a "barometer for the overall performance of the health and care system".

Senior analyst Deborah Ward said: "A&E performance is influenced by activity and pressure in other services, affecting both the number of people going to A&E, and how quickly A&E can treat them."

She said that the availability of social care services to support people at home, and how quickly wards are able to accept people who need to be admitted, were two key examples.

"Some of the pressure comes from within A&E departments," she said. "Staff shortages are particularly concerning, and many have a lack of physical space. Some departments see twice as many patients as they were built for."

“However, it isn’t relentlessly bad news,” she added. “A&E waiting times, whilst longer than we would like, are about average when compared to similar countries, and patient satisfaction is holding up.

“In July 2018, 87% of people said they would recommend the care they received in A&E to their friends and family.”

A St George's Trust spokesperson said: "Like many other NHS Trusts, St George’s experiences periods of high demand for its services - however, the majority of our patients are seen and either discharged, transferred or admitted to hospital within the four hour target.

"All patients are prioritised according to clinical need, and we have taken a number of steps to ensure we provide safe emergency care, in a timely manner, to all our patients.

"This year we opened four new ambulatory care units, including paediatrics, to enable patients to undergo prompt assessment and get the right care, at the right time, in the right place.

"This means that patients with various conditions will not have to wait for long periods in our Emergency Department, and will instead be seen by the right specialists more quickly. This also reduces the number of patients that need to be admitted to hospital."