The expanding Oddicroft Lane firm treated past and present employees and their families to a day of entertainment, including face-painting, outdoor games, a bouncy castle and a free bar and lunch.

Factory tours were also held throughout the day to allow staff to swap memories of their time at the firm dating back to 1958.

Said managing director Geoff Hall: "It's fantastic to see so many faces here to celebrate our 50th birthday. We have always enjoyed a strong foundation of loyal employees and Abacus is a family business with a real community feel.

"Abacus's commitment to pioneering products, in-depth research, environmental responsibility, rewarding careers and outstanding service, has made Abacus the genuine success story it is today. And the future looks even brighter. Here's to the next 50 years!"

The company began life as Abacus Municipal on a site in Skegby and moved to its current eight-acre site in 1962 following rapid growth.

It changed its name in 1987 and has gone on to be involved in major sporting projects, including constructing the lights at Doncaster Rovers' Keepmoat Stadium and the new floodlights at Trent Bridge cricket ground.

Abacus Lighting, which reported a turnover of £22m for its UK operation in 2007, now employees 200 people in the UK –– as well as a further 100 at a facility in Shanghai, China.