Around one third of the 200 metre by 100 metre floor collapsed on Monday afternoon at the Milton Keynes Audi showroom.

The area was used to store cars and around 20 vehicles fell through to the workshop part of the showroom below.

But staff had spotted a problem prior to the collapse and evacuated the building meaning there were no injuries.

BDB completed the showroom last August following a nine month build with a £7m contract value.

A BDB spokeswoman said that all senior staff from the Sheffield based firm had gone down to the site when news of the incident broke.

Showroom owner Jardine Motors Group said: “Part of the roof of Milton Keynes Audi, covering the workshop area, collapsed at mid-day on 1st June 2015 and the building has been evacuated.

“Nobody has been injured and we are currently investigating the cause of the collapse and the extent of the damage.”

Bucks Fire and Rescue said: “Firefighters are assisting with scene safety following a partial roof collapse at Milton Keynes Audi.

“A number of vehicles fell through to the workshop. The building was safely evacuated before it happened. No-one has been injured.”