Gledhill-Brook Time Recorders Ltd

The company was registered in 1912, when G.H. Gledhill & Sons (a company manufacturing cash registers from 1883) bought the assets and patents of the failed Stockall-Brook Time Recorders Company and went into partnership with Frank Brook. Many improvements were made to the Stockall-Brook design to manufacture a much higher quality card time recorder, using clock movements ordered in from Haycocks of Ashbourne. Built on the success of the first machines, the company went on to patent and manufacture a complete range of models, most with fusee movement options.

The company was based at the Empire Works in Huddersfield, and had contracts to supply the Royal Flying Corps and the Royal Air Force with bomb release mechanisms and other equipment during both world wars.

They continued to produce the range of very high quality time recorders up to 1964, when the failing business was sold to the Simplex Time Recorder Company (UK) Ltd.

The Simplex company was located at Southgate in London and was founded in 1963.

 Grinnell Fire Protection was purchased by Tyco in 1976. Tyco bought Simplex Time Recorder Company in 2001 and merged it with Grinnell Fire Protection, forming SimplexGrinnell.

SimplexGrinnell is an American company specializing in active fire protection systems, communication systems and testing, inspection and maintenance services with its headquarters in Boca Raton, Florida.

On September 6, 2016, Johnson Controls and Tyco completed a merger.