Mary Archer is a lucky Lady

It's not the sort of thing the Tories like to hear, but the conclusion is obvious: prison doesn't work. Lord Archer, banged up over a year ago for dishonesty, has had plenty of time to reflect on the behaviour that landed him a four-year jail sentence. But the former MP and deputy chairman of the Conservative Party is in trouble again, this time for what the director general of the Prison Service, Martin Narey, described as "a serious breach of trust".

That is one way of characterising Archer's decision to attend a party in Norfolk hosted by the former Conservative Cabinet minister, Gillian Shephard, during a day's "home release" from North Sea Camp open prison. I could come over all Tony Parsons-ish here, and demand to know whether this establishment is a place of punishment or a bleedin' holiday camp? I mean, when Archer stepped down from the dock in July last year, convicted of the grave offence of perjury, I expected him to be just a little bit inconvenienced. Not flogged within an inch of his life or anything – I leave that to die-hard Conservatives – but a teensy interruption to his famous social calendar did seem to be called for.

Yet judging by her stellar performance on Radio 4's World at One on Thursday, this is not what Lady Archer anticipated. On the contrary, she appeared to think that socialising with former Cabinet ministers was an integral part of the rehabilitation programme of Category D prisoners. I hope Lady Archer knows something I don't, namely that the Conservatives are about to announce an exciting new project whereby former ministers will take it in turns to invite inmates of open prisons to their lovely homes. Although, on second thoughts, the prospect of lunching with Lord Tebbit might be more of a threat than a promise.

The chief fascination of this thoroughly entertaining saga, as far as I am concerned, lies in trying to distinguish between Archer's routine at North Sea Camp and that of a bloke who just happens to have temporarily taken a job away from home. Until he was returned to a closed prison last week, Archer had been working every day at a theatre in Lincoln, driving himself there and back in his own BMW, eating in local restaurants and spending Sundays with his wife at the Old Rectory, Grantchester.

This sounds a rather agreeable schedule, available only to that tiny minority of inmates whose earning power is unaffected by their sojourn at her majesty's pleasure. The millionaire novelist even seems to have turned the visitors' room into a makeshift office, signing a £10m three-book deal with Macmillan there last month, and setting an excellent example for other inmates in search of ways of earning an honest crust.

Nor need we worry too much about Jeffrey's incarceration placing a strain on what Lady Archer famously described during her husband's libel action in 1987 against the Daily Star – the cause of all his recent travails – as their "full life" together. On that occasion the judge, Mr Justice Caulfield, pointed out that Archer's busy schedule of political engagements meant that he returned home only at weekends. "So is there any abstinence from marital joys for Jeffrey Archer?" he asked coyly.

Indeed it strikes me that the advantages of being married to an inmate of an open prison, for Lady Archer, have not been sufficiently catalogued. Whatever her husband got up to in the past – and the revelations at his trial last summer were nothing short of lurid – Lady Archer is now in the happy position of always knowing where he is in the evenings. At North Sea Camp, he was available at weekends when she needed an escort, and prison rules banning alcohol meant there were no arguments about whose turn it was to drive. Nor do they have to worry now, as many couples do after more than 30 years of marriage, about spending too much time together.

Lady Archer has even been relieved of reading her husband's first drafts, which was apparently taken on by other prisoners he employed as clerks. Doesn't that sound like the perfect marriage? No doubt Lady Archer feels her husband has been treated unfairly because of his notoriety. But I can't help wondering whether her annoyance is also explained by the fact that, until it all went horribly wrong, Prisoner FF8282 had turned into an ideal husband.