Huhne is on to something when he asks which ministers signed off GCHQ's Tempora programme in 2006-08

I spent the weekend with an old British friend, now resident in the US and well-versed in the world of espionage, spy-swaps and the inherent duplicity of secretive intelligence services the world over. He reinforced my view that, whatever doubts many of us had about the WikiLeaks affair or Julian Assange, Edward Snowden's data-mining revelations are of major importance to democratic debate.

No wonder then that Chris Huhne returns to the attack in today's Guardian on the triple failure of the press, parliament and the law to address the real issue that Snowden's disclosure highlights, the unaccountable accretion of sensational eavesdropping technology by the NSA and GCHQ.

I can't agree with the disgraced Lib Dem ex-cabinet minister when he calls this development the most catastrophic power-grab in British peacetime history. That strikes me as much hyperbole as the security establishment's counter-claim that Snowden's treachery is the worst in postwar British history, worse than Burgess, Maclean and Blunt at the height of the cold war, when 25,000 nuclear missiles pointed our way.

The lackey press ("45 minutes to an Iraqi missile launch on Britain", anyone?) pumped that nonsense up into "the worst leak in western history". So it's worth recalling that Huhne is a journalist by trade too, albeit an economics journalist, the modern equivalent of the religious affairs correspondent. Exaggeration is what the hacks do in all branches of the business.

But he's on to something in his article when he asks which cabinet ministers signed off on GCHQ's Tempora programme in 2006-08. Margaret Beckett under Tony Blair? David Miliband, her successor as foreign secretary under Gordon Brown? Good question and a change of elected regime is always a good moment for the permanent government to pull a flanker on untried ministers – to win political cover and pass the buck if things go wrong, as they sometimes do.

I think I have an answer to his question. But first, the context. It wasn't hard to see why Chris Huhne was cross with Whitehall two Mondays ago about the failure to tell the coalition cabinet in which he served the scale and nature of GCHQ's data-mining operations.

Huhne's indignation was clearly fuelled by the call he says he got from a senior official reminding the former energy secretary that he should not use his new Guardian column to reveal "privileged information" acquired in office. The ex-MP – whose fall from power to prison was classic hubris – retaliated by examining something he was NOT told about instead.

After going through some of Edward Snowden's cache of NSA/GCHQ files last month, the novelist John Lanchester wrote long and well in the Guardian – read this important essay here if you missed it – about why it is important that the British public, sleeping soundly when it should be concentrating, must debate how much information we should allow the state to extract from us and file in the name of security – and upon what terms of accountability.

Harry Evans, one of Fleet Street's greatest postwar editors in the heyday of the Sunday Times under Roy Thomson's benign ownership, says much the same in today's paper.

That is correct. But it is a world away from the practical business of running a coalition government in an age of 24/7 media. Which is why David Cameron may not have told colleagues all he knew.

Cabinets are important institutions whose collective role and shared responsibility is diminished at our peril if we do so in favour of rule of a quasi-president – one with presidential powers but little constitutional constraint, let alone by a shadowy cabal of key ministers and faceless civil servants.

Collective decision-making matters (it reduces mistakes by testing policy) but it's painful. That eternal battle goes on in committees, in quiet corridors but also on TV, where ministers and officials are grilled by MPs and Paxman-folk alike. Ditto the courts, as Huhne writes today. It's just more visible now – except when it isn't.

When the Labour backbencher and future founder of the NHS, Aneurin Bevan, constantly challenged Churchill in his prime as Britain's warlord between 1940-45 he made himself an unpopular nuisance. But Nye's instinct was sound.

In 1951 Bevan helped bring down the Labour government over its new chancellor's preference for war rearmament in Korea funded by NHS prescription charges. He was wrong about the NHS charges but right about the defence budget, as Churchill later acknowledged when he cut it.

In the intervening years Clem Attlee had decided that Britain must build its own atomic bomb in order to remain one of the war-time "big three" powers. He and his intimates, chiefly Ernie Bevin, trade union hero turned cold war foreign secretary, kept the secret to themselves. Why? Cabinets are leaky; there would have been a row of the kind that later fuelled the Campaign for Nuclear Disarmament (CND), the passionate if self-absorbed crusade to rid the world of nukes by setting a good unilateral example.

CND was way past its prime in the late 1970s when Jim Callaghan – like Attlee a Labour PM with wartime military service – again decided not to tell his cabinet of the decision to upgrade the warhead on Britain's US-bought Polaris nuclear missile system, the Chevaline programme which was revealed by the incoming Thatcher government in a Commons statement by Francis Pym, defence secretary.

I was present. The idea had been to ensure that at least one missile would still be able to penetrate Moscow's improved anti-ballistic missile defences and do the job of destroying the city. That's what deterrent theory was about. Those were the days!

This isn't a straight left-right cultural issue, though governments of the left tend to have more politicians with a commitment to openness, not to mention messianic self-aggrandisement, which can be harnessed to the openness agenda.

It's not as if Chris Huhne himself has always been frank about political or even personal matters. But Tory governments are instinctively more amenable to "reasons of state" arguments, more worldly you might say.

Even so Margaret Thatcher had her secrets, too sensitive to risk a leak. They all do and are entitled to have them, though they will all have to be justified in the end – or not.

How many of Anthony Eden's cabinet colleagues knew of his secret collusion with France and Israel – cooked up at Sevres outside Paris in 1956 – to seize the Suez canal back from Egyptian nationalisation via a collusive invasion? Not many. It cost him his health and job – and was all his own fault. As Churchill said of his fragile successor, I would never have dared do it, but having done it, I would not have dared stop. Eden stopped.

So the prime question I asked myself two weeks ago is the one Huhne pointedly asks today: how much did the security apparatus, GCHQ, M15 and M16, tell David Cameron – and before him all PMs as far back as John Major – about the new surveillance technologies which effortlessly outstripped all capacity to place them under legal control and constraint? And who signed off on whatever it was they were told.

It's not that what they did was criminal; there were probably good reasons at the time. Good reasons, too, why the Brown or Blair cabinet was not informed, nor Clem Attlee's. The dangers of a leak from an inexperienced cabinet in 2010, full of tension and Lib Dems, is obvious. You can see why they didn't do it, rightly or not.

But now that it's out – most things come out in the end – we need to know who knew what so that the routine claims since Snowden broke cover that Tempora and its kind are properly accountable can be exposed for the self-serving deceits they probably are.