In a house which has staff, the cook may be in charge of the kitchen but if she ever refuses to cook what her master has ordered, the master (or his butler) will come downstairs and boot her out. Do you think if there was a stand off between the UK government and IANA, that IANA would win? They are merely the technical skivvies looking after aspects of the network for the governments.
If IANA ever attempted to re-delegate .uk against the wishes of the UK government, the issue would immediately be escalated way above IANA into the ranks of UK - US government diplomacy. It is almost inconceivable that the US government would stand by IANA doing such a thing because the UK and US have good relations and such a move would be potentially catastrophic to the UK economy. But even if they did, the UK government would surely act quickly to superimpose their own duplicate copy of the previous .uk namespace so that UK business would continue with as little upset as possible. They would then call an emergency meeting with the international community to recommend switching over to a new international Internet infrastructure body to replace IANA and I suspect seeing how IANA had held one of the world's major economies to ransom, most countries would fear similar treatment (and welcome an opportunity to wrest an important international resource from out of the US's hands), jump on board and IANA would be finished with days.
But all this is beside the point. The .uk namesepace is de facto under the UK government's control, .uk is de facto a national UK asset and Nominet have been entrusted with managing it. For many years they have been charging more than is necessary for wholesale prices, building up substantial cash reserves and now they have the gall to hike prices up 50%. This is clearly the behaviour of a monopoly, not a non profit acting in the public interest.