Atomic Frequency Standards
The National Physical Laboratory took over control of the MSF Time Signal service in 1967 and introduced new Rubidium Atomic Frequency Standards and solid-state digital clocks.
The GBR time signals could be driven from the new frequency standards, giving a higher level of accuracy. However, the time signal control equipment was still the responsibility of the Post Office. Dougy Brock, the VLF Resident Engineer at that time, designed the new control equipment ‘in-house’ which was built using 74 series TTL logic. The old cold cathode clocks became redundant at this point.