But mostly the standard of catering in public places is determined by those who do the job in the first place. This is no barrier to improvements, and Peter Propper is so impressed by the job his wife, Anne, has done since she took over the Queen's Park Cafe in north- west London, last November that he rang this newspaper to say so. By way of emphasis, he added that the park's owner, the Corporation of London, was intent on improving the quality of food served in all its parks.
'Are we?' asked a corporation press officer. I decided to find out, and ate lunches in four park cafes.
The Proppers' cafe is in the centre of Queen's Park, next to the tennis courts. The rhythmic thwok of balls sounds gently beneath the screeching of children. Women in summer frocks, most with small children, occupy mismatched garden furniture. Sparrows bathe in an old water fountain. It is dreamily pleasant, and faintly shambolic. There are rubbish bins everywhere. Mrs Propper explains: 'If (the public) don't have a bin within arm's length, they throw rubbish on the ground.' Rubbish still tangles in the hedges.
The cafe itself is small, bright and cheery. A colourful collection of teapots lines the top shelf. Tennis balls are sold next to a lurid variety of crisps. I ordered pasta (fusilli with tomato sauce) and a tuna salad (tinned fish with green beans, hardboiled eggs and olives). The pasta was fine. The salad needed dressing.
I returned for pudding. Through a hatch, a middle-aged woman was visible - probably Mrs Propper's mother, who bakes for the cafe. I ordered a slice of chocolate cake, rich, moist and good, served on a paper plate with a plastic fork.
The hissing coffee machine and boxes of panetone strung from the ceiling of The Parliament Hill Cafe in Hampstead Heath give it away as being Italian-run. The owner, Alberto D'Auria, hails from Salerno and has run the cafe for eight years. Dishes called 'spaghetti nap', 'spaghetti bol' and 'chicken dinosaurs' indicate a degree of assimilation.
I ordered lasagne. Outside, there were more children, more litter. I settled inside at a wood-effect laminated table screwed not just to the floor but also to a set of orange plastic chairs.
Ten minutes later a large girl in open-back sandals flip-flopped into the room. 'Number seven]' she bellowed - and kept on bellowing until I realised that I was number seven. The pasta, served on a blazing-hot oven dish, was tough, but the filling was fine.
I was number 39 for the yelling waitress at the Osho Basho Cafe in Highgate Wood. The curious monicker combines the names of the owner (Basho) and that of his 'spiritual teacher' (Osho). It signals other alternatives: order a Coke and you get Whole Earth cola with the rainforest stimulant guarana. The menu is vegetarian.
In other respects, however, Osho Basho embraces Western indulgence. Near-naked children clutch lurid raspberry-red and lime-green ice-lollies. Adults opt for gooey but good pastries from the local bakery, Queen of Tarts, good Lavazza coffee and a decent selection of beer and wines, including a claret, an Italian pinot grigio and a Californian sauvignon blanc called 'Highgate'.
I had ordered a first-class but blazing-hot lentil, red pepper and coriander soup. It would have been perfect for November. Strangely, there were no cool summer soups on offer. Accompanying the hot soup was a basket of spongy granary bread and melting packets of Anchor butter. I ate on the lovely terrace, lyrically English, with views over a cricket ground. Less lyrical were the screaming children and customers dropping litter.
Tony Pazienti calls his cafe in Golders Hill, at the northern extreme of Hampstead Heath, the Refreshment House. Everyone else calls it 'Tony's Cafe', and has done for the 22 years he has run it.
Here, Jewish north London behaves in a decidedly Italian fashion. On a terrace overlooking an animal park with flamingos, pheasants and goats, young mothers in designer sunglasses feed their children 'home-made' gelati. Old, leather-skinned gentlemen drink pinot grigio and eat simple pasta dishes. The freshly squeezed pink-grapefruit juice is delicious. And because more food is home-made, and less prepacked, there is less litter.
The press officer at the Corporation of London had not heard of an improvement drive because there isn't one. 'We ask that all the cafes supply affordable refreshments for park-goers,' she said. They do.
Queen's Park Cafe, Kingswood Avenue, NW6 (081-960 6946). Open daily 10.30am-8.30pm, or an hour before the park closes. Lunch with beverage approx pounds 5.
Parliament Hill Cafe, Parliament Hill, Hampstead Heath NW5 (071-485 6606). Open 9am-6pm daily. Lunch pounds 2- pounds 5.
Osho Basho Cafe, Highgate Wood, London N10 (081-444 1505). Open Tues-Sun 8am-9pm, or until dusk. Lunch pounds 2- pounds 5.
'Tony's Cafe', Refreshment House, Golders Hill Park, Hampstead Heath NW3 (081-455 8010). Open 10.30am-sunset daily. Lunch pounds 2- pounds 5.