The Beaumont opens Pearl above Mayfair's public garden

Pearl Mayfair, the new all-day restaurant at The Beaumont hotel, has opened inside a converted electricity substation overlooking Brown Hart Gardens.

The restaurant sits inside a Grade II listed, early 20th-century Baroque-style building that still works as a substation beneath its dining room. When the building went up, the Duke of Westminster required a paved Italianate garden on its roof to compensate local residents for the industrial site below. That garden, Brown Hart Gardens, has just reopened after a 950 sq m redesign by the late landscape architect Nigel Dunnett, with the building restored by Studio Ageli and EPR Architects.

Lisa Goodwin-Allen oversees the kitchen as The Beaumont's culinary director. She is also chef patron-director of the Michelin-starred Northcote Hotel and Restaurant in Lancashire, and her menu at Pearl runs breakfast through dinner with dishes drawn from Italy, Spain and Greece.

A substation that spent a century humming under Mayfair now serves lunch.

Breakfast covers croissants filled with smoked salmon and scrambled egg, chorizo with feta and rocket, or truffle brie with mushroom and mizuna, alongside focaccia sandwiches and bowls. All-day dining moves into Chalk Stream trout crudo, tuna loin, glazed octopus with 'nduja aioli, a carbonara croquette with guanciale, lamb chops with sumac, grilled swordfish with preserved lemon, and pork meatballs in romesco with aged pecorino.

A pavilion built for the garden view

The dining room is a circular pavilion with curved glass fronting the gardens, deep upholstered chairs and marble-topped tables. A three-metre light fixture runs through the parabolic roof, and a five-seat bar clad in gold sits at the back of the room. Pearlescent surfaces throughout are meant to recall the coastlines of southern Europe, the kitchen's main reference point.

Dessert follows the same geography: Seville orange polenta cake, pavlova, crema catalana, gelato and aged manchego. The wine list draws from Italy, France, Spain, Greece, Croatia, Sardinia and Turkey, and the bar runs spritzes alongside classic cocktails, including a Pearl Martini made with Oyster Gin.

Mayfair's newest hotel dining room

Pearl opened in late September, in a busy season for London openings. Gobind Chona opened a second Oorja in nearby Marylebone around the same time, and both kitchens are chasing the same local lunch trade as much as hotel guests.

Breakfast runs from 8am to 11.45am, and all-day dining from noon to 9.30pm. Bookings go through SevenRooms or by phone.