In 1870, ' C ' Telegraph Troop, Royal Engineers, was founded under Captain Montague Lambert. The Troop was the first formal professional body of signallers in the British Army and its duty was to provide communications for a field army by means of visual signalling, mounted orderlies and telegraph.  By 1871, ' C ' Troop had expanded in size from 2 officers and 133 other ranks to 5 officers and 245 other ranks.

In 1879, ' C ' Troop first saw action during the Anglo-Zulu War. Five years later on 1 May 1884, ' C ' Troop was amalgamated with the 22nd and 34th Companies, Royal Engineers, to form the Royal Engineers Telepgraph Battalion; 'C' Troop formed the 1st Division, Field Force based at Aldershot, while the two Royal Engineers companies formed the 2nd Division, Postal and Telegraph based in London.

Signalling was the responsibility of the Telegraph Battalion until 1908, when the Royal Engineers Signal Service was formed.  As such it provided communications during WW1. It was about this time that Motorcycle Despatch Riders and wireless sets were introduced into service.

A Royal Warrant for the creation of a Corps of Signals was signed by Winston Churchill, Secretary of State for War on 28th June 1920.  Six weeks later;  King George V conferred the title Royal Corps of Signals.  It was given precedence immediately after the Royal Engineers.

Before WW2, Royal Signals recruits were required to be at least 5 feet 2 inches tall. They initially enlisted for eight years with the colours and a further four years with the reserve. They trained at the Signal Training Centre at catterick Camp where they were all also taught to ride.

Throughout WW2, members of the Corps served in every theatre of war. By the end of the war the strength of the Corps was 8,518 officers and 142,472 men. In one famous episode, Corporal Thomas Waters of 5th Parachute Brigade Signal Section was awarded the Military Medal for laying and maintaining the field telephone line under heavy enemy fire across the Caen Canal Bridge on D Day 1944.

The tactical white over Royal blue markings and armlets.  These colours are used for unit identification markings on vehicles, and the marking of signals offices and tactical installations. The white symbolises the white of the ribbons wound on the Caduceus of the god Hermes (the symbol of the messenger) and the blue represents the Royal Colours.  The white and blue armlets are also worn by dispatch riders but contrary to common belief.  The despatch rider was not just confined to motorcycles.  They were also recognised as being on foot, bicycle, horse or indeed any other mode of transport.  Whilst wearing the armlets; despatch riders could not be stopped or hindered by any authority or individual.  When off duty the armlets were turned upside down. 

The Corps Colours and cap badge feature Mercury, the winged messenger of the gods, who is referred to by members of the corps as "Jimmy".  The origins of this nickname are unclear however; according to one explanation, the badge is referred to as "Jimmy" because the image of the ancient Greek god Mercury was based on the late medieval bronze statue of that 'divine' being by the Italian sculptor Giambologna.  This is usually referred to as "Giambologna's Mercury" - shortening over time reduced the name Giambologna to "Jimmy".

The most widely accepted theory of where the name Jimmy comes from is a Royal Signals boxer, called Jimmy Emblem, who was the British Army Champion in 1924 and represented the Royal Corps of Signals from 1921 to 1924.

On the 6th September 1935 the King appointed Her Royal Highness, The Princess Royal, Princess Mary to be Colonel-in-Chief of the Corps.  An appointment she held until her death on the 28th March 1965.

The Corps Motto is Certa Cito which, translated, means Swift and Sure.

In order of precedence on parade the Royal Corps of Signals falls second on the right of the line making it the third most senior corps in the British Army with precedence over the Foot Guards, Infantry and services.