It need not be the gloomth of Strawberry Hill. On a hot, dusty Saturday, when the pubs are spilling onto the pavements and every bus is a greenhouse, abandon Soho and Marylebone for Kew Gardens. There is a richly silly scene in Stella Gibbons’s novel Westwood when the serially adulterous playwright Gerard Challis takes the blonde he hopes to seduce to Kew intending to make love to her among the chrysanthemums. As he leads Hilda off the path towards a shady hollow, he is greeted by an ego-deflating cry of “Grandpa!” and the sight of his small grandchildren enjoying a picnic with their frumpy nanny. All romantic hope is lost.

You quite see, though, why he chose Kew. The pagoda and cherry blossoms lend it exotic, heady appeal. Unlike London’s other parks and gardens it is walled, rather than ringed by railings, and there is nothing so romantic, courtly, chivalric as a walled garden. Walking through Kew with my university boyfriend, one peerless July day between second and final years, I felt, halfway along the cedar avenue, I might be falling in love with him and was convinced of it by the time we reached the duck pond.

I have since been dazed by the glare of sun on Canary Wharf seen from Greenwich Park and climbed the branches of an oak on Parliament Hill with two boyfriends I admired but did not love — and sat sketching opposite the stucco and stalactite grotto of Painshill Park with one I do.

A crow’s nest is a good test of a summer fling. Away from hot pavements, the distractions of restaurant queues, theatre bars, the South Bank, is the object of a summer romance likely to last after the departure of the swallows and the wiping down of the Pimms Jug pub boards?

As you cannot spend every day of a London summer in a waking dream in a park at the end of the District Line, where can you find ten minutes of coolth, gloomth, greenth and blueth in the city?

You need courtyards — Pickering Place in St James’s, half-timbered, half-shaded, behind the Lock & Co shop which sells the smartest straw hats; fountains — the Ottoman confection at Leighton House, Kensington, is pleasingly camp; and galleries with garden terraces — the Fan Museum in Greenwich, the Estorick Collection in Islington. And you need the early mornings.

I am through the gates of Kensington Gardens at six each morning in the summer. Any later and I have to share the park with runners training for the October half-marathon in show-off sweatshirts: “Yale”, “Morgan Stanley”, “McKinsey”, “If it doesn’t hurt, you’re not trying.”

From the Serpentine Bridge I can test the London View Management Framework. There is the Palace of Westminster, there too is the Shard with its lizard-tongue point and the London Eye. Walk the Serpentine’s south bank and you see the Post Office tower to the north-east, a Smash Robot made to Alberto Giacometti’s specifications. From the north bank the pinnacle of the Albert Memorial is a gold Midas finger pointing the way to Albertopolis: the Albert Hall, the Natural History Museum, the V&A.

If you were inclined, and I confess I am not, you could jump from the lido jetty. I have it from the doughty lido swimmers that the water is a brisk 16 degrees even when it is hot enough to fry eggs in the reflected glare from the Walkie-Talkie on Fenchurch Street.

Take a picnic, take Pevsner, take a Lock & Co hat. Think kindly from your crow’s nest of the hot young things jostling at bars for their Aperol Spritz.