During the Second World War, as the Blitz raged over Britain, sixty thousand innocent civilians died and fifty thousand were injured, either caught under a direct hit or trapped in a burning building. Night after night the bombs rained down as more than a million homes were destroyed, an immense amount of damage was caused to industrial installations and many public institutions were ravaged or obliterated. Consequently, all over the country, teams of voluntary fire-fighters were set up to help in emergencies. These volunteers were risking their lives. In universities staff took it in turns to sit and ‘fire watch’ in case the building was bombed or set alight. Blackout instructions were rigorously adhered to and special permission had to be obtained before work in the laboratories could be continued after dark.

Holmes took his turn fire watching in the Durham Science Laboratories along with the other members of his staff, and during the day he lectured large batches of RAF cadets who now came through the department every six months as part of their course. Unfortunately, unlike during the First World War when the call to arms reduced student numbers and increased research time, the need to ‘cram’ these RAF cadets meant that the long vacations disappeared and precious research time was almost non-existent.