Luton-based MacDonald Humfrey (Automation) was started in 1988 and it provides control systems and specialises in airport equipment. In 2013 it made £8.6m profit on nearly £44m sales. Michael Macdonald is a director and main shareholder.
Latest turnover: £44m
Five-year rise in turnover: 300%
No. of employees: 265
Five-year rise in employment: 66%