Single-needle telegraph instrument in a shaped wooden case with a needle on a plain green dial. A drop-handle for transmitting electrical impulses is positioned under a sloping desk used to hold the message being transmitted. Devices like this, used by telegraph operators to send and receive telegraph messages, were also used to transmit time signals. At pre-determined times, operators cleared the lines of ordinary messages and waited for the time signal to arrive. When the signal came, it caused the needle to 'kick'.

Most telegraph time signals in the UK originated from the Royal Observatory, with the General Post Office providing the distribution network.