SHOULD weary hacks trudging at the end of the day from The Economist’s office to Charing Cross station raise their heads, they may raise their spirits, too. Across the Strand, four storeys up, is a band of greenery, becoming lusher as the year progresses. On the roof of Coutts, the posh, private-banking arm of the state-owned Royal Bank of Scotland (of which the queen is said to be a customer), Peter Fiori, the head chef, oversees a thriving garden, home to a host of plants and three beehives.

“We have four microclimates,” Mr Fiori says, as he walks along the thin strip between the troughs in which the produce grows, stopping to pluck a herb, crush it and invite you to smell it, or to pop it into your mouth. Warmth from the roof on the south side, he says, adds several degrees to the temperature. Thus above one of London’s busiest streets guavas, pepino melons and finger limes, plus all manner of berries and wasabi, a pungent-rooted Japanese plant notoriously fussy about its surroundings, are grown for client lunches and dinners. The garden was built by Mr Fiori’s late friend, Richard Vine, with help from The Clink, a charity for prisoners.

Coutts is not alone. Several other local rooftops in central London—including those of the Canadian High Commission, the London School of Economics, the National Gallery and the Savoy hotel—boast rooftop gardens or hives. Late last year the Northbank Business Improvement District, which among other things aims to improve air quality and promote biodiversity in the area around the Strand, was named one of five “business low-emissions neighbourhoods”, sharing in a £1m ($1.3m) fund. Local air quality is among the poorest in the capital.

London has more than 5,000 hives, says Natalie Cotton of the London Beekeepers Association, ten times the density of the rest of the country, although how many are on roofs isn’t known. Ms Cotton says that keeping bees on top of buildings isn’t always practical anyway. A full “super”—the part of a hive where honey is made—weighs more than 20kg, so takes some lifting; and bees expend a lot of energy to get to hives more than a few storeys up.

Many of London’s 140 bee species are struggling, says Ms Cotton, because of a loss of suitable forage in gardens and elsewhere. On the roof of Coutts, Mr Fiori is doing his bit, planting bee-friendly plants such as mint, lavender, sage and chives. “It’s important to give something back,” he says. What goes around comes around: last year Coutts’ hives yielded 12kg of honey. A jar is thought to have found its way to Buckingham Palace, a mile away as the bee flies.