I recently spoke on the telephone to Monica Maurice in her office at the Wolf Safety Lamp Company, the Sheffield-based specialists in safety lighting engineering, with a world-wide reputation second to none. On that occasion her son John Jackson (my twin brother), now managing director, and her grandson, a graduate in design engineering, were poring over a technical problem with her. Her father, William Maurice, founder of the company, who purchased the business rights from Friemann and Wolf of Saxony in 1910, would have been proud to have known that three further generations were thriving as a result of his vision and insight.

Yet it was not easy for Monica Maurice, who on her own, after her father's death in 1951 and with the aftermath of the Second World War, had to restructure and rebuild lost markets and demands. The company has now changed almost beyond recognition. No more flame lamps or acid batteries are now made by the company. The intense noise of the fly presses, the scream of turbine wheels and the clank of blanking machines from the shop floor have given way to the production of the "Wolf light", a light portable, rechargeable hand lamp with the power of a motor-car headlamp, that could be dropped from a 10-storey building and would not break.

Monica Maurice was brought up in the industrial north Midlands, the eldest of three daughters all of whom were educated at Bedales. She had a talent for languages and design and studied at the Sorbonne, in Paris, and at Hamburg University in the late Twenties. Even as a young girl there was a steely determination to be successful.

Her long and distinguished career started in February 1930, first as secretary to her father at the company, then as a trainee with the old parent company in Zwickau. This was the first of many visits to Germany throughout the Thirties. On one occasion she wandered into a restricted zone and saw what she thought was a guidance system. This she reported to the British authorities on her return, but they were not interested. At the outbreak of war though, she was summoned to London for a three- day debriefing. All this experience, her knowledge of technical German and her familiarity with many of the industrial sites proved invaluable.

In 1947, with the rank of lieutenant-colonel, she participated in a British intelligence overseas survey mission to Germany to determine the extent and subsequent recovery in certain specialised industries. During this visit her party were reporting their arrival at a town near Cologne when an arrogant young British captain dismissed their request for accommodation and supplies. Monica Maurice came forward and quietly suggested that she might be forced to pull rank and suddenly rooms were available in the local hotel, as well as fuel and rations for the onward journey. It was only recently that the fascinating and revealing diaries made on her visit to Germany were discovered and it is the family's hope to publish this, together with other of her papers.

She married a Canadian doctor, Arthur Jackson, in 1938, and by the mid- Fifties was ferrying three children to and from Bedales, where she was a governor for eight years. These journeys were made in a wonderful Mark VI Bentley and were a joy to her children often clutching large baskets of cherries procured from the Thames Valley roadside.

Monica Maurice's passion for cars and planes was insatiable. She learnt to drive the family Singer Swallow at Park Grange, the family home overlooking Sheffield. By the Thirties she had graduated to a Donnington track model chain-gang Frazer Nash with which she would race her friend Joy Davison. Both were members of the York Aviation Flying Club at Sherburn in Elmet, North Yorkshire, some 40 miles away. The plan was that they would breakfast at Park Grange, then set off each in their own cars. The Frazer Nash was small, nimble and light with tremendous acceleration, so that Maurice would have a good lead by the time she joined the Great North Road. But on the fast sections of the last 10 miles Davison's huge powerful car would haul in the Frazer Nash so that they would arrive at the clubhouse together.

By the late Thirties Monica Maurice drove a Brough Superior Drophead Tourer and raced one of the works' Brough supercharged hill-climbing cars. She moved on to a pre-war BMW 327, and after the Bentley came a wonderful primrose yellow DB2 Mk III Aston Martin with a works engine which one could hear coming from miles away.

Her latter years were spent at peace in the tranquil village of Ashford in the Water in the Peak District of Derbyshire, where she enjoyed regular visits from family, friends and most of all her grandchildren, whom she adored.

William Jackson

Helen Monica Maurice, lamp manufacturer: born 30 June 1908; managing director, Wolf Safety Lamp Company 1951-79, chairman 1951-88; OBE 1975; married 1938 Arthur Jackson (two sons, one daughter); died 20 September 1995.