A man who was mowing the grass outside Norfolk County Council's headquarters had to be taken to hospital - after the vehicle he was in toppled over.

An investigation has been launched by the maintenance man's bosses following the bizarre incident, which left the man and his vehicle lying upside down on a car park.

It happened on a grass bank opposite the main forecourt car park at County Hall in Norwich on Tuesday lunchtime.

The man, who works for Norse, an arms-length company owned by the county council, was in a vehicle he was using to cut the grass on the bank.

The grass bank is raised above the County Hall car park and, for reasons which have yet to be established, the machine and its operator tumbled off the wall.

They landed, upside down, on the concrete below - a drop of about three-and-a-half feet.

An ambulance was called and the injured man was taken to the Norfolk and Norwich University Hospital, although he was not kept in.

Norse, which has the contract for maintenance on the County Hall site, confirmed an investigation into what went wrong was under way.

A spokesman for Norse said: "We are currently investigating the circumstances surrounding an incident at County Hall on Tuesday lunchtime, in which a member of staff working for the County Hall grounds team was slightly injured.

"We will be talking to witnesses concerned and reminding staff to be sure to follow all relevant guidance when mowing on slopes.

"We are pleased to report the individual concerned was not detained at hospital and hopes to be back at work shortly."

The Norse Group was formed in 2006, after two county council-owned services (Norfolk County Services and NPS Property Consultants) came together.

The group provides services to the public and private sector across the country, including a number of contracts with Norwich City Council.

The city council last year wrote to Norse informing bosses of the authority's 'strong intention' to take back in-house all four contracts which it has with the company.

The council had hoped the switch would happen by April, but the deadline passed without agreement being reached.