Tucked behind Charing Cross Road, this is a super spot for a leafy lunchtime break. The plants, flowers and wildlife in the garden are all maintained by volunteers. Look out for frogs and sparrows, which are thriving thanks to an enthusiastic conservation initiative. After exploring, pop into the nearby churchyard of St Giles in the Fields for weekly food stalls and delicious coffee from Rosie & Joe’s Coffee Stall.

A short walk from St Paul’s Cathedral lies one of London’s most touching monuments: George Frederic Watts’s ‘Memorial to Heroic Self-Sacrifice’. Within the quiet Postman’s Park, nestled beneath a tiled roof, are just over 50 ceramic plaques, each commemorating an ordinary person who lost their life trying to save others. Many of the descriptions are truly heartbreaking, and you can easily spend an entire lunchbreak contemplating their selflessness.

Tucked away in Abney Park, you'll find Abney Park Cemetary, where Salvation Army's founders are buried, among others. Creep through the overgrown woods of the cemetery, past the crumbling gravestones, and you will eventually emerge into a large central clearing dominated by the menacing shell of a derelict chapel. The impressive gothic-revival building dates from 1840, but was gutted by fire in the 1970s and closed.

Barnsbury Wood was once the garden of George Thornhill, who built the surrounding houses in the 1840s. But stroll through the wood to find the real hidden gem here, its nature reserve, which is the smallest in London. Snuck between houses in affluent Barnsbury it was originally a vicarage garden. After being abandoned in the 1840s a woodland naturally grew and the Barnsbury Wood is now home to the sixteen spot ladybird. Please note: dogs are not allowed.

Thousands wander across Hampstead Heath's wild and undulating parkland every year, but very few discover this eerie and elegant pocket of faded grandeur on the West Heath. Built by Lord Leverhulme at the start of the twentieth century as a setting for his extravagant parties, it includes impressive gardens and a dramatic elevated walkway, where overhanging plants create a lush canopy and tangled roots twist around smooth stone columns. A little window into the world of the Edwardian super-rich.

Across the road from the better-known Highgate Wood, there is something more magical and quiet about Queen’s Wood – witness its hilly pathways through the oak, beech, mountain ash and cherry trees. It might be only a few hundred metres from Highgate tube station, but native bluebells, wood anemone and countless species of small animals and creepy crawlies make this a wonderful retreat.

Between the generous expanse of Hampstead Heath and the bustle of Royal Free Hospital is a small garden with noble ambitions. The World Peace Garden actually does live up to its name. It's a really peaceful woodland glade with three ponds and a wishing well, making it a perfect spot for some quiet meditation. Residents and traders are responsible for rescuing what had been a wasteground area alongside Hampstead Railway Station for over a century - their words are immortalised on the walls.

Brockwell Park is no hidden gem to Londoners, but its secret walled garden is much lesser known. Four unassuming walls near the western edge of Brockwell Park enclose one of the most enchanting – and perhaps only – respites from the buzz of Brixton. The urban clamour melts away as you meander along stone pathways, between beds of vibrant plants and flowers, to discover bubbling fountains and secluded benches. This was once the kitchen garden for Brockwell Hall, but is now an oasis of calm.

You know Crystal Palace Park, but have you discovered its maze yet? This network of head-scratching hedgerows is almost as old as the dinosaurs – the Crystal Palace dinosaur sculptures, that is (had you going there, didn't we?). Dating from around 1870, the puzzle is tucked away near the park's northern lake. After falling into disrepair, it was renovated in 2009 to commemorate the centenary of the Girl Guides.

Walk through Mordern Hall and an ancient mill, where Kingfishers perch on reeds by the riverbank, and an old-fashioned waterwheel is slowly turned by the gentle current. It sounds more like an idyllic country village than a public space just a few minutes’ walk from the Northern line, but therein lies the charm of Morden Hall Park. Once the sprawling estate of a wealthy family, it's still home to watermills that used to grind tobacco into snuff.

The thick stone walls of this bombed-out medieval church have been almost smothered by nature and it makes for a curiously peaceful experience within the throb of the City. Leaves, vines and branches poke, cling and climb to this Grade I-listed ruin. Perfect for atmospheric folk/prog-rock band photos and some quality daydreaming. The church can also be hired out for events of 45 people, if you're looking to get hitched sometime soon.

This award-winning secret garden just around the corner from Hoxton Overground has a focus on food-growing and promoting wellbeing – many of the passionate team of gardeners have long-term health issues. It may only be 0.7 hectares but boasts working beehives, a polytunnel, woodland, wildflower meadow, a pond populated with newts and is completely accessible to wheelchair users.

The oldest botanic garden in London quickly became a world leader in natural medicine after opening in 1673. Its location next to the Thames in Chelsea is no accident – the river’s proximity creates a warmer microclimate meaning rare and endangered species are able to thrive. Within its walls 5,000 different edible medicinal plants grow including the world’s most northerly outdoor grapefruit tree.

A picturesque waterfall flows into a peaceful rock pool, where koi carp dart beneath the surface and peacocks stalk past on the banks. It might sound like the setting for a Japanese fairytale, but this is, in fact, one of west London’s most serene spaces: Holland Park's quaint Kyoto Garden. It’s the perfect spot to unwind with a book, linger with your thoughts or fight your samurai rivals to the death.

Step away from the aggressive redevelopment of Dalston Junction into this community garden, where locals grow fruit, vegetables and flowers on the site of a former railway line. It's open to the public all year round, and its popular café is a fine place to enjoy coffees, pizzas, and botanically inspired cakes. Plus, check out this garden's programme of events for community garden sessions, music nights, and kids craft clubs.

This Islington community garden is a haven for local residents, who cultivate organic fruit and veg and stunning flower beds. If you want to pop in regularly, annual keyholder membership is £10; alternatively, free public access is on Saturday afternoons from noon til 4pm, and on Sunday afternoons from noon til 4pm from May til September.

The bright colours in this woodland garden are so vibrant that any visiting hippy might be forgiven for thinking he's in the throes of an intense acid flashback. The rich reds, pinks and purples of blooming rhododendrons and azaleas line the pathways amid hidden ponds and tranquil clearings. Richmond Park as a whole is a delightful place, but this enclosed 42-acre space would give any garden in the world a run for its Monet.

Tucked behind the Angel and Chapel Market is this friendly community garden. Residents, local groups, market traders all find refuge amongst the 50 winding plots, with two for disabled gardeners. It may be quite small but it’s still possible to find a quiet spot to enjoy a sandwich or soak up the sunshine. When some flowers went missing the garden’s response was to put up a cartoon artist’s impression of the thief drawn by one of the volunteers. It’s that kind of a place.