Re: oh, boy ...
In front of me is the highly technical first edition of the ICL "Network News" - January 1976. The front page editorial "Networks - The Way Ahead? " is from Peter Hall, the director of the Government and Public Corporations Division. Fascinating reading.
It opens by referencing ARPA and Infonet. That is followed by mentioning some large UK private networks - several of which were nationalised industries eg CEGB and SW Universities. It then mentions the nationalised Post Office's Experimental Packet Switching System (EPSS).
What is really interesting is that the future is seen as standardised, but private, packet networks to link mainframes and their in-house users - like IBM SNA at that time. It is considered that the Post Office EPSS would be limited by price and availability - and would not expand fast enough to accommodate the needs of big users.