Festival-goers heaped extra pressure on already stretched medics as drink-related casualties flooded into A&E after Pride.

A boy of 13 suffering a suspected drugs overdose was one of hundreds of people who packed Royal Sussex County Hospital in Brighton A total of 405 people were seen by medical staff - the majority reportedly alcohol-related cases with many underage.

The hospital’s A&E normally sees about 300 patients on Saturdays, 70 more than other days of the week, but numbers rose by a third throughout the main event in Preston Park and the evening that followed.

The St John Ambulance team who worked voluntarily in Preston Park also treated 210 people over the day - most of whom did not go to A&E.

Pride organisers are due to meet police, hospital bosses and the city council later this month to discuss the running of the event, which drew 150,000 visitors to Brighton, and lessons for the future.

Among the casualties taken to hospital was a 13-year-old boy who was found collapsed and not breathing in Preston Park.

A tube was inserted in his throat and he was taken to accident and emergency suffering from a suspected drug overdose.

No information has been released about what drug he was believed to have taken.

He was admitted to the Royal Alexandra Children’s Hospital but walked out as soon as he regained consciousness.

Both police officers and hospital staff reported seeing a high number of young teenagers suffering from the effects of alcohol.

Other alcohol-related patients included people who had suffered minor injuries while drunk.

Dan May, St John Ambulance’s assistant commissioner for Sussex, said: “The rain meant that everyone was very wet including the casualties who were arriving at our treatment centres and so as well as dealing with their various conditions we also had to keep them warm.

“We unfortunately had some very poorly people come our way who were looked after in our intensive care area and some of them did end up being taken to local hospitals.”

A spokeswoman for Brighton and Sussex University Hospitals Trust said: “As is often the case when Brighton and Hove hosts major events such as Pride, the Royal Sussex County Hospital was exceptionally busy over the weekend and our staff worked exceptionally hard over what was a very challenging 24 hours.

“It was a challenge that everyone rose to and all the 400 patients who came into our A&E department on Saturday was treated and either admitted or discharged in a timely and appropriate way.”

Police who searched suspected drug users said they found several substances believed to be the party drug GHB, as well as cannabis, cocaine, ecstasy and ketamine.

In total police arrested six people for possession of drugs with intent to supply and seized substances from several more people who did not face formal action.

Of the other 11 arrests, four were for affray, two for public order offences, one for drunk and disorderly behaviour, two for breaches of anti-social behaviour orders, one for theft of a mobile phone and one for domestic violence.

On Saturday afternoon Superintendent Steve Whitton said: "Given the substantial numbers we have seen, it has been a peaceful and successful event with very few isolated incidents.

“I'd like to thank all the organisers and participants for making the event such a great success."

Judith Manson, Pride’s communications manager, said she could not comment on specific details until organisers meet the other agencies involved.

She said the weather had made the job of people running the event more difficult.

She said: “We are really proud of the work that everybody does, from our security to everybody on the ground.”