The time signal used to set Britain’s clocks with extreme accuracy is on the move from Rugby, where it has been transmitted since 1927, to a new home in Anthorn in Cumbria. The signal, often referred to as ‘The time from Rugby’, will be known as ‘The Time from NPL’ from April next year.

The time signal is accurate to within one thousandth of a second and supports several rail services. Most rail operators use the signal to underpin their communication systems and signalling. It is used to monitor trains across the network and the clocks at most mainline stations are also tied to the National Physical Laboratory’s (NPL’s) time signal.

The National Physical Laboratory is home to the nation’s atomic time and one of only five laboratories worldwide using the latest caesium fountain to contribute to the world time standard Coordinated Universal Time (UTC).The signal’s transmission is tied to NPL’s atomic clocks at Teddington in South West London.

The switch will follow a three-month test period between January and April 2007. During these periods the signal at Anthorn will be switched on for short periods of time. These are opportunities for rail engineers to ensure their equipment can receive the new signal before the old one at Rugby is switched off. Anyone wishing to test their equipment against the new signal should sign up for signal testing schedules by clicking here.

NPL managing director, Steve McQuillan, said ‘Maintaining accurate time is essential to keeping the


’s rail system working. Many rail organisations use the signal constantly. We regularly notify those we know who may be affected by our testing and we’ll be happy to add any other users to our email list if they get in touch. However the vast majority of time signal users will not experience any disruption during the testing and switchover.’