Around 1.4 million people in Blighty are unable to get speeds of 10Mbps, according to Ofcom's annual Connected Nations report.
However, that is an improvement on last year, where 2.4 million, or 8 per cent of the population were unable to get 10Mbps.
Unsurprisingly, rural areas still lag behind on broadband, with a quarter of rural properties (nearly 920,000) – unable to receive the "the speed required to meet a typical household’s digital needs".
But, according to the report, the UK has the fifth best availability of broadband services offering 10 Mbps - ahead of almost all European countries, but behind Singapore, Japan, South Korea and the Netherlands.
Ofcom said it remains concerned that the UK has very low coverage of "full fibre" broadband. Here the UK ranks seventeenth out of 19 countries. It currently has just 2 per cent fibre-to-the-premises penetration.
The government is legislating to provide a USO of 10Mbps by 2020. But it has yet to flesh out the details of what that will look like.
So far, its preference is to force industry to pay up, whereby companies providing the service would recover costs from a fund paid into by a range of telecoms companies.
Steve Unger, Ofcom group director, said it was "unacceptable" that so many people were still struggling for a good service.
“So we’re challenging mobile operators to go beyond built-up areas, and provide coverage across the UK’s countryside and transport networks. Today we’ve also provided technical advice to support the Government’s plans for universal, decent broadband.”
The regulator has advised on three scenarios for a USO, which will cost between £1.1bn-£2bn. These include a standard broadband offering a 10Mbps; a more highly specified version of this service; and a more expensive superfast broadband service.
Speaking in Parliament yesterday, Skegness MP Matt Warman and former technology editor of The Telegraph said: "Ofcom has not yet defined the 'U' the 'S' or the 'O' bit of the USO. We must acknowledge that there will be areas that it is not economical to connect, just as we do with water or electricity."
Concerns have been raised that BT is so far the only supplier to step forward and offer its services in exchange for favourable regulatory conditions.
But Warman said a single company might not necessarily be the right approach - adding that even a company as big as BT "will not be providing every part of the solution."
He said that "[i]n the manner of the Low Pay Commission, Ofcom should make recommendations each year to see the USO rise incrementally." ®