This has led to improvements not only in reliability, but also in safety; in the latter field, for example, Denis has investigated over 40 incidents involving crankcase explosions and air compressor fires and explosions.

In 1975 he was awarded the Tribology Silver Medal for services to mechanical engineering.

He has been a director of Neale Consulting Engineers carrying out consultancy assignments world-wide since 1984. He has also lectured widely on their tribology of machines course. Denis has recently been acting as an expert witness.