The chief executive of the company that installs the majority of speed cameras on Britain's roads was banned from driving for six months today after admitting driving at more than 100mph.

Tom Riall, the boss of Serco's civil government division, which supplies and installs the Gatso fixed radar cameras to police forces, was travelling at 102.9mph on the A14 in Newmarket, Suffolk, just before 1pm on 4 January, magistrates in Sudbury heard. The speed limit on the dual carriageway is 70mph.

Riall, 49, had two other driving convictions from the last three years, including another speeding offence, the court heard, meaning the six-point penalty imposed by magistrates took him past the 12-point mark, incurring the ban. He was also fined £300.

Riall, who took part last year in a road safety campaign called Safe Drive Stay Alive, told the court he would like formally to apologise, saying: "In my role I am all too aware of the consequences of speeding." Riall said he was driving to visit friends in Newmarket before a business meeting in Norwich and the road was clear.

He asked magistrates not to impose a ban, saying it would cost about £30,000 to employ drivers to take him on business trips during the six months, and that the speeding offence had already caused "some considerable personal embarrassment".

He said: "Of course, while I have had a number of fixed penalty notices in the past, this is the first time I have exceeded the speed limit to this degree." The magistrates rejected this, saying a six-point penalty was fair.

Serco, which has installed about 4,500 speed and traffic light cameras since 1992, began as a defence firm and over the years has won a series of lucrative government contracts in areas which also include prisons, leisure centres and NHS facilities.

Riall, who joined Serco four years ago and became chief executive in January 2007, is a former soldier who served in Northern Ireland and Cyprus before entering the business world.