Fifteen people were evacuated from the St Margaret's Tesco Express store as smoke billowed from its plant room about 12.30pm.

Fortunately, the 30 children in the Gymboree nursery and toyshop next door had left half an hour before smoke started coming through the vents in to their play room.

Firefighters are attacking the blaze from the front and back of the convenience store in the strip of shops in St Margaret's Road.

Along with Tesco and Gymboree, the next shop along, Superdrug, has also been evacuated.

At 1.15pm, smoke was covering St Margaret's Road, shrouding the nearby railway station, but trains continued to run.

The six staff inside the Tesco Express noticed the smoke coming from the shop's plant room about 12.20pm, shortly before the fire alarms sounded.

A London Fire Brigade spokesman said four fire engines with about 20 firefighters were on the scene.

A total of six fire units, including an investigation team and fire brigade photographer were on the scene, with crews rotating because of the hot weather. A brigade spokesman said firefighters expected to be on the scene until at least 4pm. A total of 60 people were evacuated from the shops during the emergency.