All of which said, it is an odd business, isn't it? Either he knew about these armaments contracts or, as he assures us, he did not. If he did know, then he is chin-deep in liquid unpleasantness, and sinking. If he did not, then his former business associates are remarkably mistaken.
The arms business is considered to be a bit wacky. It is one of those trades which are either heavily government-sponsored and controlled, or else exist on the edge of commercial life, in a lurid half-light in which odd coves congregate and fortunes are suddenly and inexplicably made. Sometimes, as with the Matrix-Churchill affair, the gamey flavour of private arms-dealing intrudes into government. A smell of cheap cigars, and worse, eddies through the corridors of power, and it takes a judge and an inquiry to fumigate the place.
It is not surprising that this world of arms-dealing attracted Aitken, who is a Tory romantic, as addicted to the glamour of the Orient, and to the wealthy and powerful, as Disraeli himself. He is a risk-taker, a double-or-quits man. Sheikhs and rockets are rather his bag.
Furthermore, the late Eighties was the time when corporate Tory Britain seemed to go a little crazy. The spirit of the age was reckless, triumphalist. There were no limits. Whitehall nervousness was mocked, even by ministers. I vividly remember having lunch with one such who derided and abused the arms embargo on the two sides in the Iran-Iraq war as liberal-leftie nonsense.
But politicians don't go mixing with the private arms trade without paying a penalty. Sooner or later, like a disreputable old acquaintance who suddenly appears with a sinister grin at your elbow in the club, the past catches up. In this case, however infuriatingly, it just has.
Do not expect him to go easily, or undefended by his colleagues. He is a fighter. He has waited many long years for his chance as a cabinet minister - kept out, according to rumour, by Margaret Thatcher's anger at his jilting of her daughter. He has already proved tenacious in defending his position against the stories about his Ritz hotel bill which surfaced in the Guardian - a story which, like this one, turned on questions of trust and the details of paperwork.
Since then, he has displayed a political energy that shames many younger and longer-in-office colleagues. He has proved an inquisitive and radical Chief Secretary to the Treasury , stalking hospitals and burrowing deep into the internal organs of GCHQ in his quest for savings.
He is liked and, it seems, trusted, by the Prime Minister. It now seems pretty clear that his attack on the BBC was no piece of freelance activity, motivated by petulance, but the first shot in a licensed and planned attempt to cow the Corporation ahead of a run of bad election results. That doesn't reflect well on Aitken, but it suggests that he is close to Downing Street. One cannot imagine Michael Portillo being called in and asked to spearhead such an operation.
Aitken helps Major merely by not being Portillo and thus, perhaps, splitting the right-wing caucus at some future stage. Nor has Aitken behaved disloyally, at a time when many others have. He has been discreetly approached by backbenchers who want him as leader, and has sent them away. He tells friends that a challenge to Major would be disastrous.
In short, of all the Cabinet, Aitken is now something like fourth or fifth in the list of those whom the Prime Minister can least afford to lose. He may be the newest entrant and formally the most junior, but he is far more important than that. He is a flash of glamour in a grey team. He entertains in a fine Westminster house where Brendan Bracken sheltered Churchill in the Thirties, and keeps close contact with the American right - Henry Kissinger stayed with him after the ``Britain in the World'' conference this week. He is a candid friend to other ministers and a cheerer-upper. It would demoralise the Government badly to lose "Jonathan"; they will fight for him almost as hard as he will fight for himself.
They will do so, above all, because there is a sort of collective ministerial paranoia about the hit-rate of the press. One put it like this: "When I look around me, and think how many of my generation have already had their careers blown away, because of sex or because of money, I feel like a survivor of the first days of the Somme." The fall of Rupert Pennant- Rea at the Bank of England only adds to a sense that the Establishment is being slaughtered by scandal.
Such talk turns individual dilemmas - stay or go? - into a wider struggle for dominance between politicians and the press. The Scott Inquiry, whose report into not dissimilar matters is so apprehensively awaited, may turn out to be a defining moment in that struggle. But before the Government battens down the hatches and throws itself into doggedly defensive mode, there are at least a couple of lessons it needs to learn, and fast, from the Aitken story.
First, it can try again to remember that commerce and governance require different cultures, and a habit of public thinking that keep them apart. This discriminating sense was lost in the late Eighties and it is not clear that it has been recovered. It was, for instance, bizarre to give Aitken, with his background, the arms procurement portfolio at the Ministry of Defence as his first substantial government job. Nothing "happened" as a result of that decision - it provoked no front pages. But for the Prime Minister to think that this, rather than education or health, was the right place to start him showed a curious insensitivity, at best.
The second message, surely, is for all ministers, former ministers and ministers-to-be. Whatever the truth about there being no free lunches, there are no free £10,000-worth of directorships. These are not sinecures, but carry serious responsibilities - not least the responsibility to be nosey. MPs are not asked on to the boards of companies for their shrewd entrepreneurial streak or their pretty face. They are paid good money because they are wanted to open doors in Whitehall or abroad, or because business executives reckon they can provide political cover in a hard and dirty world. On the board, they are assets to be milked for a return. It is nave to think anything else: and in the end, my nagging concern is that Mr Aitken makes such an unlikely naf.