What happened
When BT was sold off in 1984 it controlled the entirety of the UK's telephone and emerging data infrastructure. Rather than restructuring BT before privatisation to require open-access infrastructure investment — as France did with France Télécom — the Thatcher government simply transferred the public monopoly into private hands intact.
BT faced no competitive obligation to lay fibre. When the internet era arrived, BT rolled out ADSL over copper — because copper was already there and fibre was expensive. Successive regulators (Oftel, then Ofcom) were too weak to force BT's hand. The result: by 2020 the UK sat 35th globally for full-fibre broadband coverage, behind Romania, Lithuania, and Portugal.
This wasn't just a market failure — it was the direct consequence of a privatisation design that put no strings on the buyer. The government could have required open-loop unbundling, a universal fibre rollout obligation, or retained infrastructure as a public asset while allowing private service competition. It chose to do none of these things.