Lytaloy was a product of Hobbs of Barbican. They produced brakes, headsets, cranksets, bottom brackets, and pedals. It is thought that the components were produced by outside contactors and they were regarded as top of the line parts. Lytaloy was very expensive at the time.
The cranks look great but were prone to breaking. This set of cranks looks suprisingly well for a 50+ year old cranks that usually only lasted a couple years, or less.
Via Bicycle 