Pools in one of the country’s favourite open spaces will welcome visitors on Saturday but others will stay closed, with the Government said to have made the announcement on reopening with no prior warning.

Hampstead Heath’s four outdoor swimming facilities will reopen with a new online booking system following Government guidelines about outdoor pools announced on Thursday.

The Heath’s Ladies’, Men’s and Mixed Bathing Ponds as well as the Parliament Hill Fields Lido will initially be limited to early morning sessions as the City of London Corporation tests new safety procedures.

This is welcome news to the hundreds of thousands of Londoners who enjoy the bathing ponds and Lido every year

Another pool reopening is Charlton Lido in south-east London, which will welcome a small number of guest swimmers on Saturday ahead of a general opening to the public from Monday.

But Everyone Active, which manages five outdoor pools on behalf of local authorities in Plymouth, Hemel Hempstead, Stroud and Ashby-de-la-Zouche, said its facilities will be among those remaining shut.

A spokeswoman for Everyone Active, said: “We are aware of the Government announcement yesterday, which confirmed outdoor pools can reopen from July 11.

“We had no prior warning of the announcement date, and therefore we are discussing with our respective local authority partners the arrangements for reopening at the moment.

“We will be in touch with customers soon to confirm the details and the date for reopening of all our facilities.

“We thank everyone for the patience and support whilst we work as quickly as we can, in partnership with the Councils.”

The Serpentine lido in London’s Hyde Park, which reopened this week to members of the Serpentine swimming club, will remain closed to the public.

A Royal Parks spokeswoman said: “Our project to expand and upgrade the changing facilities has been put on hold due to current circumstances.

“We will not be opening the public swimming facility in the Serpentine at the present time as we are unable to do so safely.”

The spokeswoman elaborated that it is the “size and configuration of the small changing rooms” which makes it unsafe to open.

City Corporation said lifeguards working on Hampstead Heath have received specialist training with adaptations to allow them to maintain social distancing if they need to assist swimmers in the water.

Staff are also bringing in enhanced cleaning and new signage to assist swimmers with the new safety measures.

If the weekend’s early morning public sessions run smoothly and safely, extra swimming sessions will be added to allow for more swimmers to access the ponds and the lido.

Anne Fairweather, chair of the City of London Corporation’s Hampstead Heath management committee, said: “We are delighted to begin safely reopening Heath’s swimming facilities after getting the green light from the Government, who responded to our call to allow outdoor pools to open swiftly.

“This is welcome news to the hundreds of thousands of Londoners who enjoy the bathing ponds and Lido every year.

“We are asking all swimmers to respect the new safety arrangements, and recognise that we have limited capacity with these Covid-secure restrictions, as we welcome people back.”

Mark Sesnan, CEO of Greenwich Leisure Limited, said he is “delighted” about the reopening of Charlton Lido.

“It’s one of the few places in London that’s open for outdoor swimming,” he added.

“We’ve been closed for nearly four months and like our regular customers, our staff have been itching to get back open.

“Charlton Lido is a hugely popular community venue that celebrated its 81st birthday this year. We’ve got customers who came on the first day it opened.

“Of course, while swimming is one of the safest leisure activities because chlorine kills the Covid, we do have safety top of mind.

“Everything – from pre-booking to restricted volumes to sanitisation – has been carefully thought through to give customers total confidence to get back in the water.

“And with double lanes and a maximum of 12 people per lane at any one time – it’s going to make for much more space for your swim and a hugely enjoyable experience.”