Electrically-corrected dial clock, numbered 4543, fitted with Lund's patent synchronizer. Signed ‘The Standard Time & Telephone Co. Limited’ and ‘Synchronized clock, Lund's patent 4543’ on the white-painted dial with Roman numerals. The clock is housed in an ebonised wooden case with brass bezel and a gilt beading around the case-front.

The basic clock is a conventional spring-driven pendulum-controlled wall clock with fusee movement and anchor escapement. However, on receiving an hourly electrical synchronisation signal delivered by wires connected to a 'master clock' (often several miles away, and in some cases from the Royal Observatory in Greenwich), a pair of pins which protrude through the top of the dial at the XII position move down a crescent-shaped track to the centre position, and then are released back to their upper, rest, positions. If the minute-hand of the clock was anywhere between :59 and :01, it is brought exactly to the :00 position when the signal is received. The clock is thus corrected every hour for errors of ± one minute per hour.

John Alexander Lund, of Barraud & Lund, Cornhill, London, took out patent 3924 for this synchronisation mechanism on 11 October 1876. The Standard Time & Telephone Company was set up to market and supply this service with these clocks.

For historical and technical details of the Lund system, see ‘The Horological Journal’ for April 1878, pp. 105–107 and an advertisement on page iv. of that issue, placed by Barraud & Lund.