Just as Babylon’s hanging gardens were one of the seven wonders of the ancient world, Kensington’s rooftop gardens are among London’s most glorious follies. One hundred feet above the high street lurks 1.5 acres of themed parkland, complete with four flamingos and an air fleet of resident ducks, one of whom lands in a stream in full view of our window table. In such a setting, Richard Branson’s bright and breezy brasserie doesn’t have to go out of its way to pull in the crowds. And nor does it. The greeting was chilly; service was perfunctory and remote; and the food, while perfectly competent, did not deliver the quality or quantity that the steepish prices might suggest. A pressed mosaic of Devon Rose chicken, liver and aubergine terrine was gorgeous to look at, but served fridge-cold with a vapid garlic and parsley dressing, while a nicely simple mixed seafood grill was let down by mushy langoustine. A starter of barbecue asparagus had the flavour of the grill, but just four spears seemed mean, leaving it to a roast fillet of cod with gruyère and parsley crust and flaky ham hock – and the gardens - to save the night.