IMAGES TAKEN NEAR TO
Woodcock Hill, ST. ALBANS, AL4 9HQ

There are two of these centres, one here and the other in Langhurst, Sussex. They are for government scientific research. https://www.gov.uk/government/collections/centre-for-applied-science-and-technology-information

The original site began 1939 as a wireless intercept station for the Foreign Office operated by GPO radio engineers and was used to intercept diplomatic traffic between enemy governments and their embassies. Initially the messages were in morse code but later Germany used high speed encryption and transmission equipment that needed to be recorded by undulators, a mechanised paper strip inking system. The results were sent by teleprinter to Bletchley park for decryption. The messages were of the highest value to Winston Churchill who received assessments every day. After WW2 it became part of the Diplomatic Wireless Service and remained largely unchanged until 1973 when it was handed over to the Home office. Sources - National Archives file HW55/3 & HW14/102, http://www.ystations.webs.com/

Intriguing – This old-fashioned looking radio mast is stuck on the top of a minor hill in the Hertfordshire countryside and looks most incongruous. The map marks it as a wireless station and there are some mysterious road signs to “HOSDB”. I must find our more ... Image

Entrance to the research centre

Situated at the HOSDB research centre

This is obviously a farm refurbished as business premises

Looking almost straight into the sun from TL185104 at the signal mast on the road coming east out of Sandridge. No normal phone mast this; the thing's ringed with two layers of razor wire fence and has a sign at the entrance with a royal coat of arms on it. Photo notes: for better results take photo in morning, not afternoon like I did - the mast's partially obscured by trees from the west, so better to be east of it with the sun behind you.

Looking E to the signal mast at TL184103.