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Lidos in London have tightened security after a spate of chaotic poolside incidents - including one which saw a sunseeker smashed over the head with a bottle.

Workers at Parliament Hill Fields Lido in leafy Hampstead Heath have told how break-ins, brawls and boozing forced the spot into closure twice this summer.

It comes as Britain grapples with a record-breaking drought which has seen some areas go a staggering 59 days without a drop of rain.

Temperatures are forecast to soar to a peak of 38C on Thursday during the sixth heatwave of this year, meaning the country's outdoor pools could hit capacity.

Yet London's lidos have spent much of the summer contending with a 'concerning' rise in antisocial behaviour.

Dozens of sunseekers were filmed taking a plunge in Ruislip Lido despite warnings stating that swimming was prohibited, meanwhile organisers at Tooting Bec's pool were forced to increase security in a bid to tackle surging attendances.

And video footage shared with the Daily Mail this week displayed one shocking incident at north London's Parliament Hill which left a visitor in hospital.

A crowd of youths are seen embroiled in a huge poolside fight over the May Bank Holiday weekend as lifeguards - some of whom are later pushed into the water - desperately try to restore order.

Video footage shared with the Daily Mail shows a huge poolside brawl over the May Bank Holiday weekend at Parliament Hill Fields Lido in north London

The clip shows hordes of youths fighting as lifeguards desperately try to restore order

Parliament Hill lido has been forced into closure twice this summer amid 'inappropriate behaviour' from visitors

Security guards at Tooting Bec Lido in south London check customers' bags at the door - and no one can enter without a wristband

The eye-opening incident was sparked after a swimmer was slammed over the head with a stolen wine bottle, according to witnesses who said youths had forced their way onto the site.

A waitress at the lido's cafe, situated just a stone's throw from homes worth more than £1million, told the Daily Mail: 'We have a lot of break-ins. They stole a wine bottle from us and smashed it on this guy's head.

'A lot of them were really drunk and they pushed a lifeguard in. The man was bleeding across his head.'

The victim was rushed to hospital before two men were arrested, but later released due to a lack of information.

Regulars, however, say that such incidents are far from uncommon at the north London lido, nestled in a quiet corner of Hampstead Heath's sprawling 800 acres.

When the Mail visited this week a frustrated manager told how 'brawls break out every summer' and knives have been found hidden in visitors' bags.

He added: 'There's something happening every summer. We've had knives and stuff in the past. It used to be really bad.

'We've had issues in the cafe too. We've had people trying to jump over the counter because they couldn't get booked in.

'In the summer it's common for fights to break out. This is a posh area but it borders not so privileged areas. It's mostly kids, they can't drink in the pool but I suspect they probably do before they come. We used to have issues with people smuggling bottles in, but I don't think so anymore.

'If I was here with my kids (when the fight broke out), it would have been really concerning.'

In the wake of the violent incident, the City of London Corporation (COL) - the body which runs the site - was forced to impose stricter rules in a bid to ensure good behaviour.

They included a ban on under-16s entering without a parent, random bag searches, additional security and ID checking. Pictures this week also showed how 10-foot-high walls have been installed in a bid to deter sunseekers from climbing in.

But just days later a fight was said to have broken out as swimmers waited for upwards of 40 minutes in lengthy queues outside. Eventually, at the end of June, the lido closed for two consecutive evenings due to 'poor behaviour'.

The site, situated within Hampstead Heath, has since chosen to install 10-foot-high walls to stop sunseekers climbing in

Swimmers caused havoc a few hundred yards away at Hampstead Heath's Model Boating Pond in May

Such problems are however not consigned to Hampstead Heath's outdoor pool. During the same period, hordes of sunseekers caused havoc at a wildlife pond situated a few hundred yards away.

Dozens descended upon the Model Boating Pond for a dip during May's heatwave despite the water being a 'no swimming zone' and safe haven for nesting birds.

The groups ignored signs as boisterous swimmers were filmed scaring groups of ducks, throwing balls amongst each other and playing blaring music on the banks of the water.

Furious residents described the protected habitat as a 'party destination' and accused swimmers of showing a lack of respect.

One fumed: 'It's absolutely terrible what they're doing. They are violating absolutely everything it's supposed to be and it's so upsetting.'

Videos which emerged from Ruislip, west London, in May showed a packed out lido with dozens of people in the water despite the site's red flag flying.

The flags typically mean there is no lifeguard on duty and there are hidden hazards present, such as poor water quality or toxic algae.

Yet many took the risk to take the plunge amid warnings from authorities about the danger of taking to the water without the proper assistance or supervision.

The latest figures produced by Better, the leisure company which runs the London Fields, Charlton and Oasis swimming pools, reveal that some 524,988 visited those three sites between June and August 2025.

That figure marked an increase of 30 per cent on the same period a year earlier, meaning the number of Londoners flocking to outdoor pools this summer will likely have increased again.

Jem Collins, who runs the online guide All The Lidos, says antisocial behaviour is caused by casual visitors, rather than swimmers who visit lidos all year round.

She told the Mail: 'I do think that this summer there have been more incidents than I've been aware of recently, and that is due to the heatwave. It got hot in May and it really hasn't stopped.

'You have 500 to 1,000 people queuing outside of a pool, getting hot, and waiting to get in. That's when tensions start to rise and things start to fizz.

'I think sometimes people have an expectation that they're going to be sat by the pool with a cocktail, almost as if they're abroad, but that's not really what lidos are like in the UK - you wouldn't find a poolside bar anywhere.

'The lido scene here is much more about the water and the swimming, and it's open to anyone. If you want to sit in the sun and not do much swimming then that's fine... but what it isn't, is the boozing and the "lads, lads, lads" environment.'

Tooting Bec welcomes more than 3,300 per day at its busiest and boasts the country's largest outdoor pool

At Tooting Bec Lido, the country's largest outdoor pool, security levels are increased depending on the number of visitors. Bags are checked at the door and no sunseekers can enter without a wristband.

At its busiest, the south-west London site welcomes more than 3,300 visitors per day - but incidents of antisocial behaviour are rare, according to security guards.

One said as temperatures hit 27C on Tuesday: 'We have more of an issue with there being too many people than customers getting aggravated. Anywhere that's got a big capacity, there's always going to be people that do things.

'If it's busy, we have about six security guards, it changes depending on how many people are here. They run the place really well here.

'You can see where it's going though. As the UK gets hotter in somewhere like London, there's no seaside, no water, so everybody who wants to have a beach experience goes to their local pool.

'It's something that I think is going to be a big problem. I think with public spaces if there's a mass congregation of people anywhere, there's always going to be problems.

'It's like when you go to a festival, what's the difference between that and being somewhere where there's loads of people. You get the same kind of results.'

A spokesperson for the Metropolitan Police said of the incident at Parliament Hill Fields Lido in May: 'At around 16:56hrs on Monday, 25 May, officers were called to reports of an altercation at Parliament Hill Fields Lido, Camden.

'Officers attended the scene and located a 15-year-old boy and a man in his 40s with minor injuries.

'A boy, aged 17 and a man, aged 25 were arrested on suspicion of affray.

'Anyone with information is asked to contact police on 101, quoting CAD5578/25MAY, or Crimestoppers anonymously on 0800 555 111.'