Their investigations started with one question - how do you get clothes clean? They looked at many answers including the type of detergent, the movement of water through the clothes, rubbing the fabrics together, flexing the fibres, temperature and time.

They designed rigs to test each aspect in isolation and, after four months of research, discovered the astonishing fact that 15 minutes of handwashing gets clothes cleaner than 67 minutes in the then best performing washing machine!

This is because the most effective way to release the dirt is to flex the fabric fibres, as you do when you wash clothes by hand.

Test rigs took many shapes and forms, from a series of jets forcing water through the fabric, to a rubber bag pummelled by mechanical fists.