I think Nominet has been shitting themselves over new gTLDs.
Although Nominet has a monopoly on the UK namespace extension, they're scared that thousands of new gTLDs such as .shop, .photography, .sports etc will dilute the UK market and make .co.uk less of a default domain for UK business.
As such, I think they're trying to find new ways of adding value to a UK extension so that it doesn't disappear in the fog of new gTLDs. By offering something more secure, possibly restricted to UK companies, I think that helps their long term strategy.
Of course, the obvious issue for them is balancing the future of their company with new services whilst placating those customers on .co.uk.
I'm not sure if it's just me but I do see a trend of bigger UK companies using the .com instead of .co.uk (e.g. MoneySupermarket, GoCompare, Sky, nPower etc)