In a nice coincidence, one hundred years ago Jock Kinneir was born in the same hospital as my sister would be much later. Later still, I was to join the Ministry of Transport a few years before Kinneir and Calvert's typeface was officially chosen for all highway signage. MoT staff were treated to a showing of the promotional film explaining the background to the letter design and the choice of colour for motorway signs. "Motorway" had been tried out on the Preston by-pass in 1958. Later, the "Transport" alphabet was developed and "Transport Medium" and "Transport Heavy" fonts adopted for all roads in the UK. Some other countries adopted "Transport" and an alphabet for the NHS grew out of them also.
Perhaps "Helvetica" might not have been so swiftly accepted in the UK if "Transport" had not come along first.