Dame Stella Rimington, director general of MI5 until 1996, recently helped to create a nerve-shredding drama packed with edge-of-the-seat cliffhangers.
Larger-than-life characters battle for the soul of one of Britain's most august institutions as ferocious predators lurk in the shadows, and a twist-packed plot lurches from one tense stand-off to another.
But that's enough about the struggle for control of Marks & Spencer, where Dame Stella has been a king-making (and king-breaking) non-executive director since 1997. Yesterday, she also published a thriller about MI5, At Risk (Hutchinson, £10.99). Here, the results feel more off-the-peg than made-to-measure.
The book, trumpeted for its behind-the-scenes view of intelligence operations by a "uniquely qualified" insider, offers a sturdy but conventional hunt-the-terrorist plot. In paperback-suspense terms, it really does read like the counterpart of one of those robust, risk-free, M&S outfits its agent heroine, mid-thirties Liz Carlyle, observes on the backs of her drab fellow-spooks at their Millbank HQ. Just don't expect any kind of designer creation.
Our ostensible villain - surprise, surprise - is an Islamist terrorist from an Afghan family. He sneaks into East Anglia, with undisclosed plans for a strike on a high-profile target.
Soon, he links up with a mixed-up, middle-class Englishwoman who has gone over to the side of the jihadi militants. This faith-seeking renegade, Jean D'Aubigny, is among Rimington's many updates of cold war spy-story conventions for the age of al-Qa'ida.
Liz, our intuitive sleuth, is aided in her chase-against-time across the wintry fields of Norfolk by respectful coppers, but thwarted by a vile, public-school smoothie from MI6. In fact, we end up loathing the smarmy, deceitful Bruno Mackay far more than the holy warrior, Faraj Mansoor, who turns out to have credible and "entirely personal" motives.
So much for claims that spiteful recrimination between Britain's domestic and overseas intelligence networks is a thing of the past.
Neither do our American friends come out smelling particularly sweet.
The biggest disappointment comes from the near-absence of genuine inside information. Of course, At Risk - scrutinised by Rimington's successors - would never have seen the light of day otherwise.
Apart from smatterings of trivia about the Thames House citadel of MI5, there's little that a sedulous reading of non-fiction exposés and rival thriller-writers would not yield.
You will find the "recipe" for C4 plastic explosive on pages 241-243, although I trust that it contains plenty of deliberate mistakes.
In short, At Risk delivers an entertaining ride that owes more to the tried-and-tested machinery of its genre than to any de-classified revelations.
And the plot-device of a limited hit by a pair of lone jihadis - more assassination than atrocity - feels quaint in the wake of the Madrid train massacres.
What we need from Stella Rimington is the novel she can never write: a morally ambiguous, Le Carré-style drama rooted in the murky domestic intrigues of the M15 she served so well.
This agency spent our money and its time infiltrating the peace, anti-apartheid and trade union movements, kept tabs on generations of young radicals such as Jack Straw and Peter Hain, and got into bed with deeply unsavoury elements in Northern Ireland.
In her 2001 memoir Open Secret, Rimington glossed over this real history that she knew and shared. Here, she breathes not a word of it. Except in one, decidedly odd reference: the crooked fisherman whose death from an armour-piercing round unleashes the entire plot is named Ray Gunter.
The actual Ray Gunter was minister of labour under Harold Wilson, a union fixer from the Labour right who may (through an outfit called IRIS) have been an intelligence contact during MI5's long war against shop-floor Communists.
What memory is being stirred, and what score settled here? Dame Stella will probably never tell us, but I'd love to know.
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