A report by industry body Ofcom has revealed that while broadband speeds in the UK are increasing, the gap between advertised and actual speeds is widening.

The report, claimed to be based on the UK?s most comprehensive broadband speeds research, reveals that the UK?s average actual fixed-line residential broadband speed has increased by over 25 per cent over the past year, from 4.1Mbit/s to 5.2Mbit/s, as internet service providers move to offer higher speed broadband packages.

The lack of widespread availability of fast broadband is currently the major factor holding back the development of 'video on demand' content delivery in the UK. If the current problems could be solved, it would pave the way for a broadband-based entertainment network which would change the face of broadcasting. But even if urban broadband speeds could be brought up to speed, there could still be problems delivering similar services to rural areas.

The Ofcom report states that nearly a quarter of UK fixed-line residential broadband connections have an advertised speed of above ?up to? 10Mbit/s in May 2010, compared to just 8 per cent in April 2009, but there's a growing gap between the actual speeds delivered and the speeds that some ISPs use to advertise their services. Differences are usually caused by old-fashioned copper telephone wires, long and poor quality lines, electrical interference and workload. The Ofcom report summarised thusly:

Headline (Advertised) speed Average actual speed

?Up to? 8/10Mbit/s DSL packages*                            3.3Mbit/s
?Up to? 20/24Mbit/s DSL packages                           6.5Mbit/s
?Up to? 10Mbit/s cable services                                 8.7Mbit/s
?Up to? 20Mbit/s cable services                                 15.7Mbit/s

In April 2009, average actual (or download) speeds were 4.1Mbit/s, 58 per cent of average advertised ?up to? speeds (7.1Mbit/s).  In May 2010, average download speeds were 5.2Mbit/s, 45 per cent of average advertised ?up to? speeds (11.5Mbit/s).

The research found that cable broadband services delivered significantly faster actual (or download) speeds than comparable DSL services: for instance Virgin Media?s ?up to? 10Mbit/s and ?up to? 20Mbit/s cable services delivered average download speeds around twice as fast as DSL (copper wire) packages with the same or similar headline speed. Virgin Media?s ?up to? 50Mbit/s cable service was the fastest service tested, delivering average download speeds of around 36Mbit/s with single thread tests and around 46Mbit/s with multi-thread tests conducted between 4 and 6am. A single thread test involves downloading a single file, while a multi-thread test involves conducting three file downloads simultaneously, which is more typical of the way heavy internet users consume broadband.

In the light of the report, Ofcom has strengthened its voluntary code of practice by which ISPs commit to give consumers a more accurate and consistent estimate of the maximum speed, and has dropped broad hints that the Advertising Standards Authority should look into possibly misleading advertising.

Ofcom?s updated broadband consumer guides can be found here: http://consumers.ofcom.org.uk/guides/.