The founder of stadium and rock concert security firm Rock Steady yesterday sold the business he set up almost 30 years ago.

Mark Hamilton, chairman of the Edinburgh-based firm and majority owner, has joined other shareholders in agreeing a deal with security group G4S for an undisclosed sum. He is likely to have banked several million pounds from the sale.

The other minority owners are fellow Rock Steady directors Sylvia Hamilton, who is Mr Hamilton's wife, and Fred Cucchi.

Established in 1980, the group provides security across the UK for pubs and clubs, as well as stewarding for major sports events and concerts.

Its clients include Rangers Football Club, the Sheffield Arena and Lancashire County Cricket Club.

Industry veteran Mr Hamilton, 51, also headed up security for Live 8 events in Edinburgh and London three years ago.

He described the decision to sell up as "easy". "It's a really positive move," he said.

In its last financial year, the Rock Steady group turned over £12.2m. It has gross assets of £5.3m, and employs a total of 2200 full and part-time staff.

The buy-out will see the company rebranded as G4S, with Mr Hamilton staying on as managing director for a new G4S events division.

Mr Hamilton added: "We have been successful year on year, but the events industry requires a more complete approach to staff development and operational innovation.

"I could see the benefit for the people that have worked for me - it provides them with much more opportunity."

G4S was formed in 2004 from the merger of Securicor and Group 4.

The group said the deal would allow it to expand into the live music and sports stadium sector, and provide additional industry coverage in Scotland and the north of England.

Mr Hamilton is now head of security for former Beatle Sir Paul, as well as Scotland's T in the Park music festival.

He was involved in arguably last year's highest profile concert - the Led Zeppelin reunion at London's O2 arena.

The group also manages sports stadiums including Hampden Park, Murrayfield and Rangers' ground Ibrox.

The biggest crowd he has looked after is 300,000, for a McCartney concert in Rome.

He declined to reveal how much Rock Steady was bought for, but said he looked forward to going to work at G4S.

He said there was also no threat to jobs as a result of the deal. "This is a really good business to be in, and we are always looking to expand and increase our workforce," he added.

Pete Irvine, managing director of Edinburgh-based Unique Events, who has worked with Mr Hamilton on various projects, said: "We have worked with Mark Hamilton for a very long time. They are a great company."