The possibility of transmitting signals from one point to another by electrical impulses without a connecting wire had attracted attention since the early days of telegraphy, and the Post Office, among others, conducted experiments in this field. In 1896, the Post Office (through its Engineer-in-Chief, Sir William Preece) provided facilities for Guglielmo Marconi to conduct experiments in the field of wireless telegraphy by means of hertzian waves.
Marconi gave the first demonstration of his new systems of wireless telegraphy before members of the Post Office administration on 27 July 1896. With the transmitter on the roof of the Central Telegraph Office in Newgate Street, London, and the receiver on the roof of GPO South in Carter Lane, 300 yards away, signals from the transmitter were satisfactorily recorded. In August, the Post Office permitted Marconi to experiment with wireless equipment on Salisbury plain and elsewhere. The ensuing trials demonstrated the practicality of his system.
The following year Marconi was granted a British patent for his system by which "electrical actions or manifestations are transmitted through the air, earth or water by means of electric oscillations of high frequency". In July of the same year, Marconi parted company with the Post Office and, with other backers, set up the Marconi Wireless Telegraph and Signal Company.
In order to secure the control of wireless telegraphy, the Wireless Telegraph Act was passed in 1904 rendering it illegal for persons to install or work apparatus without a licence from the Postmaster General. In 1918, the Wireless Telegraphy Board was set up to coordinate interference problems in radio communication in the English Channel. The interests of users of radio other than Government departments were represented by the Post Office.
In 1924, the Marconi Wireless Telegraph Company entered into an agreement with the British Government for the provision of radio stations to set up an Imperial Wireless Chain in England, Australia, Canada, India and South Africa. From 1929 electrical communications across the Empire were overseen by the Imperial Communications Advisory Committee, on which the Post Office was represented.