Members of Parliament must be feeling under assault, with much that they hold dear, from secret expenses claims to privileged conversations with constituents, suddenly under attack. One day we the public want to know how much Hillary Worthy, MP, claims for weekly food for the family (yes, they really can claim that - it is part of the “additional housing allowance”); the next, the security Establishment is demanding the right to bug her phone. Exactly how open does an honourable member have to be?

The Wilson Doctrine, which prevents MPs' telephones from being tapped, has long been under attack by the intelligence agencies, who believe that the greater scrutiny and regulation surrounding intercepts today means that MPs need no longer enjoy specific protection. Less than two years ago, after furious representations from MPs, Tony Blair rejected the advice of Sir Swinton Thomas, who was then Interception of Communications Commissioner, that the doctrine should be scrapped; Sir Swinton has accused MPs of acting without logic, purely out of self-interest or possibly (and patronisingly) “lack of understanding”. Now backbenchers are reacting to the news that one of their number, Sadiq Khan, was recorded visiting a constituent in jail, as though the fundamental principles of democracy are under threat.

Not many beyond Westminster are going to be particularly bothered by the news that the police bugged a suspected terrorist, whoever he was talking to. (Perhaps they should be bothered that the constituent, Babar Ahmad, has been held for four years without charge, but that is a different argument.) Most people can easily distinguish between eavesdropping on jail visits and routinely bugging an MP's phone.

Will they, should they, care if the Wilson Doctrine is dropped and the specific protection afforded to MPs is removed? Many backbenchers are on extremely slippery territory here, and this is why: the current crop of MPs has overseen, allowed, passed into law, a vast expansion of surveillance over the ordinary citizen.

As Sir Swinton put it in his 2005-06 annual report: “The work of the commissioner has changed and grown out of all recognition since I took up my post in April 2000.” The nine agencies with the power to intercept letters and phone calls - the security and intelligence services, three police chiefs, Revenue & Customs - have been joined by no fewer than 786 other organisations, which, since 2004, have been allowed to ask for communications data such as the identities of whom we phone or write to, and the internet sites we visit. These organisations include all local authorities, police forces, prisons and other bodies such as the Financial Services Authority, Ambulance Service and Independent Police Complaints Commission.

In the last nine months of 2006 these bodies made 253,557 requests for data from personal communications for purposes ranging from protecting public health to collecting tax, or in the interests of public safety or “the economic wellbeing of the United Kingdom”. Which could cover pretty much anything. More than 1,000 mistaken interceptions were made; nearly 4,000 the previous year.

In the same period, the Home Secretary authorised 1,333 warrants to intercept telephone calls or letters. And about 350 bugs were placed by police and Revenue & Customs in the year from March 2006-07.

This explosion of sticky-beaking, much of it done in the name of combating terrorism but even more of it not, has occurred on the watch of the same MPs now protesting their right to an almost unique degree of privacy. Their constituents are entitled to ask: and where were you when we wanted you to protect our rights? Ah, yes, in the voting lobbies, nodding them away.

That isn't all. Most individuals will not have felt personally stung by the darts of hidden surveillance. But the increasing amount of upfront electronic surveillance, from speed cameras through congestion charge monitors to the aggressive letters from TV licensing cautioning that they are “watching you”, has struck all of us. And no, I haven't even touched upon biometric ID cards, electronic patient records, lost computer discs and the rest of it.

There are other electronic webs, too, that have us paying demands for a council tax we do not understand, or parking fines we think we never deserved, or for utility bills that seem to come from nowhere, all under threat of computer-generated court summons and without a human being who can explain any of it. Citizens are routinely being blackmailed (pay up or you are electronically blacklisted), quite legally, by electronic systems. And MPs have been abysmal at protecting the public from it.

Now they ask public opinion to protect them from electronic surveillance. As it happens, I think communications between MPs and their constituents should be protected, the more so the more we are all spied upon by state bodies and private corporations. It's no good asking people to understand that in certain circumstances their conversation may be recorded. The bond of confidentiality is then broken. If a citizen cannot be certain that his conversation with his MP, often the last resort of the desperate, is utterly private, then the core function of an MP starts to crumble and there begins to be no point in having her at all. It's the really useful role that MPs do perform, still - to be a voice for the dispossessed and the most needy. I cannot think of anything more important that they do.

But they haven't half shot themselves in the foot in making that case for themselves.

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