The British did not have a separate Corps of Signals in the Great War: it was agreed that an independent unit would be formed in 1918, but for various administrative reasons it was delayed until 1920.
At the outbreak of war in August 1914 all the British Armies signalling/ intercommunication requirements were met by the Royal Engineers Signal Services (RESS) that was formed in 1908. Previously, in 1870, the responsibility for all military communications was officially given to the Telegraph Troop, of the Royal Engineers.
A despatch rider (or dispatch) is a military messenger, mounted on horse or motorcycle (and occasionally in Egypt during World War I, on camels
Despatch riders were used by armed forces to deliver urgent orders and messages between headquarters and military units. They had a vital role at a time when telecommunications were limited and insecure. They were also used to deliver carrier pigeons.
In the British Army, motorcycle despatch riders were first used in the World War I by the Royal Engineers Signal Service. When the War Department called for motorcyclists to volunteer with their machines for despatch work at the start of August 1914, the response was huge.
The London office had 2000 more applicants than places, and a similar response was reported in regional centres around the country. If a rider and machine were approved then £10 was paid immediately, £5 to be paid on discharge (unless due to misconduct), and pay was 35s per week. The motor cycle would be taken over at valuation price, or would be replaced with a new one at the close of operations. Enlistment was for one year or as long as the war might last. The preference was for 500cc single cylinder machines and the horizontally-opposed twin cylinder. All machines had to have a "change speed gear". A list of spare parts was also required to be carried.