There’s an interesting article below stating that BT were working on fibre in the 1980s and the nation could have had faster internet sooner if it wasn’t for Mrs Thatcher’s intervention to promote cable as an alternative
How old decisions crippled modern UK connections
www.techradar.com
“At that time, the UK, Japan and the United States were leading the way in fibre optic technology and roll-out. Indeed, the first wide area fibre optic network was set up in Hastings, UK. But, in 1990, then Prime Minister, Margaret Thatcher, decided that BT's rapid and extensive rollout of fibre optic broadband was anti-competitive and held a monopoly on a technology and service that no other telecom company could do.
"Unfortunately, the Thatcher government decided that it wanted the American cable companies providing the same service to increase competition. So the decision was made to close down the local loop roll out and in 1991 that roll out was stopped. The two factories that BT had built to build fibre related components were sold to Fujitsu and HP, the assets were stripped and the expertise was shipped out to South East Asia.
"Our colleagues in Korea and Japan, who were working with quite closely at the time, stood back and looked at what happened to us in amazement. What was pivotal was that they carried on with their respective fibre rollouts. And, well, the rest is history as they say.”