The grounds of a London housing estate, the slide in a children’s playground and a memorial landscape to US president John F Kennedy are among more than 20 treasured post-war gardens and sites that have been listed for protection.

Historic England (HE) said they all show “incredible thought and care” for the people who use them, while some mark “significant turning points in the history of English gardening”.

The sites have been added to the Register of Parks and Gardens, part of the National Heritage List for England.

The sculpted formal landscape at the housing estate in Alexandra Road Park in Camden, north London, took shape from 1968 to feature walled and sunken play areas, open spaces plus lime, cherry and plane trees.

A large slide in the children’s playground which is part of the designed landscape at the Brunel Estate in Westminster, central London, has been listed.

HE describes the setting as “the most complete public housing project” by Michael Brown, a leading landscape architect of the 1960s and 1970s.

It has earth-mounding and play areas formed out of complex brickwork.

The body adds that “very few items of play equipment have been listed, and this is a particularly ambitious and inventive creation”.

The Kennedy memorial landscape in, Runnymede, Surrey, was designed in 1964-65 by Sir Geoffrey Jellicoe for the British government and the Kennedy Memorial Trust.

The work, designed to reflect the international regard for President Kennedy, features water meadows associated with the signing of the Magna Carta and the development of democratic government.

Denmans Garden in West Sussex, where influential garden designer John Brookes opened a garden design school, plus Campbell Park, which connects new town of Milton Keynes, Buckinghamshire, with the wider landscape beyond, are now also on the protected list.

The “striking” landscape around the Cummins Engine Factory in Darlington, County Durham, is another highlight, according to HE.

Memorials, the grounds of housing estates, institutions and private houses, as well as commercial and industrial sites, are also among the places which have been listed.

The Awakening Sculpture at Roper’s GardenS in Chelsea, London, and the Jellicoe watercourse at the former Cadbury Factory on the Wirral are among some eye-catching structures which have been set in the landscapes that now have a Grade II listing.

HE chief executive Duncan Wilson described each of the landscapes given protection as “special”.

Mr Wilson pointed to Broadwater Park, Buckinghamshire, “which gave out-of-town office staff a pleasant place to stroll at lunchtime,” Sir Geoffrey Jellicoe’s watercourse at the Cadbury factory, which “delighted” passing workers with its cascades and weirs, and praised designer Beth Chatto’s site in Colchester, Essex, as “the birthplace of a revolutionary planting style that continues to influence gardening today”.

He added: “These past few months have taught us that our green open spaces improve the quality of the environment around us, are good for our wellbeing and give us breathing space.”

Dominic Cole, president of The Gardens Trust, said: “Twentieth-century heritage landscapes have often been overlooked and undervalued, so we hope that these additions to the register will throw a spotlight on the importance and quality of post-war designed landscapes.”

Among the places which were upgraded or listed are:

– Beth Chatto Gardens, Colchester, Essex (Grade II)

– York Gate Garden, Leeds, West Yorkshire (Grade II)

– Denmans Garden, Fontwell, West Sussex (Grade II)

– Shute House, Shaftesbury, Dorset (Grade II*)

– Kennedy Memorial landscape, Runnymede, Surrey (Grade II)

– Alexandra Road Park, Camden, Greater London (Grade II*)

– Brunel Estate, Westminster, Greater London (Grade II)

– Golden Lane Estate, City of London (Grade II)

– Water Gardens, Burwood Place, Edgware Road, Greater London (Grade II)

– Churchill Gardens Estate, Pimlico, Greater London (Grade II)

– Fieldend, Twickenham, Middlesex (Grade II)

– Alton East & Alton West, Roehampton, Greater London (both at Grade II)

– Campbell Park, Milton Keynes, Buckinghamshire (Grade II)

– Harlow Town Park, Essex (Grade II)

– Roper’s Gardens, Cheyne Walk, Chelsea, Greater London (Grade II)

– The Improvement Garden at Stockwood Park, Luton, Bedfordshire (Grade II*)

– St Catherine’s College, Oxford (upgraded from Grade II to Grade I)

– Cummins Engine Factory landscape (Grade II)

– Jellicoe watercourse at the former Cadbury Factory, Moreton, Wirral (Grade II)

– Broadwater Park, Denham, Buckinghamshire (Grade II)

– Stockley Park, Uxbridge, Greater London (Grade II)