I assume its a holdover from the Government Secure Intranet that was designed in the 1990s by Cable and Wireless, one of the UK's main telecoms infrastructure c

I assume its a holdover from the Government Secure Intranet that was designed in the 1990s by Cable and Wireless, one of the UK's main telecoms infrastructure companies at the time and which was only privatised in the 80s. C&W was taken over by Vodafone. https://en.m.wikipedia.org/wiki/Government_Secure_Intranet https://en.m.wikipedia.org/wiki/Government_Secure_Intranet