Marconi Hall Street - The World's First Wireless Factory
Marconi came to England in 1896 and was invited by Sir William Preece, Chief of Engineer to the General Post Office to demonstrate his "Wire-less" invention. After a few years Marconi had been awarded sufficient contracts for him to require a permanent factory and took over an abandoned Silk Mill in Hall Street, Chelmsford in December 1898.

The Hall Street building was used by Marconi in 1899 (left) & (right) Plaque denoting the Marconi presence

It is considered Marconi came to Chelmsford as:-

• It was near to London, the financial centre of England
  
• It was just over 30 miles from London and so outside the area in which the General Post Office had an absolute monopoly of all Telegraphic Communications
  
• There was plenty of electrical power available as Christy Brothers had power stations there
  
• There were plenty of manufacturing works (Cromptons) with a ready supply of skilled workers.
• There were no electric trams, a source of radio interference

Adjacent to the Hall Street building, the wireless legacy is also marked...

New Street
By 1911 the Hall Street factory was just not big enough and so the cricket ground alongside the railway station in New Street was acquired and London Architects Dunn & Watson were commissioned to draw up plans for the first purpose built radio factory.   The new factory was started in February 1912 and quickly completed in just 17 or so weeks later using 500 bricklayers.