The recommendation is a result of a "research shows that the average broadband speed in November/December 2010 was 6.2Mbit/s – less than half (45 per cent) of the average advertised broadband speed of 13.8Mbit/s." (see first table below).
In addition, "Ofcom is also setting out what the TSR might be for each technology used to provide fixed-line broadband .. The new, strengthened Code of Practice comes into force in July 2011." (see 2nd table below).
See "Average broadband speed is still less than half advertised speed" - here.
A similar, even more consumer oriented initiative was announced in Israel recently (see "Regulation [Israel] - ISPs Should Publish Minimum Speed! (in "Mbps")" - here).