Six fire engines and around 35 firefighters were called to a fire in a restaurant with flats above on Upper Berkeley Street in Marylebone, W1 during the early hours of Saturday morning.
The blaze left part of the restaurant’s basement kitchen, its ground floor dining area and its ducting - the restaurant's extraction system – between the basement and second floor damaged by fire.
Around 40 people left the building before the Brigade arrived and one man was treated on the scene for smoke inhalation by London Ambulance Service.
A London Fire Brigade spokesperson said: "It looks like the fire was caused after a charcoal grill ignited grease and fat deposits in the restaurant’s ducting.
"Restaurant and take-away owners should always take care to make sure their extraction systems are kept clean as a build up of fat and grease within the filters can lead to a fire.”
The Brigade was called at 0048 and the fire was under control by 0224. Crews from Paddington, Kensington, Soho and Euston fire stations attended the incident.