The departure of top politicians generally creates one job for their successor and another for whoever is hired to ghostwrite their memoirs. But William Hague, who resigned from the Foreign and Commonwealth Office on 14 July, will be expected, as a published author of political biographies, to tell the story himself. Hired typing fingers, however, are unlikely to be left idle. Four of the top six titles in the most recent Sunday Times non-fiction bestseller list are ghosted memoirs (including those of Hillary Rodham Clinton and Joey from The Only Way Is Essex) and as one of the other books is the biography of a dog, only Thomas Piketty’s Capital in the 21st Century contains no element of creative seance. Assisted life-writing is a flourishing art and a science for which a fascinating and engaging textbook is now available.

Confessions of a Ghostwriter reveals the secrets of Andrew Crofts, who helped to popularise the “misery memoir” by putting in the heavy word work for books including Stuart Howarth’s Please, Daddy, No. A complete list of his 80-plus projects is impossible because, as he explains, ghostwriters are increasingly required by their contracts to delete their own name. Even when writing about aborted commissions, he must keep an eye over his shoulder for a wigged figure. In a chapter magnificently titled “Sacked by a Glove Puppet”, Crofts is legally unable to identify the TV character whose handlers he antagonised with a too-frank manuscript.

Most often, withheld identities have no effect on the heft of the anecdotes. Crofts was twice asked to write autobiographies with an intended print run of one: the authors were a dying man wanting to leave an account for his future grandson and a divorcing wife who planned to pressure her husband into paying more alimony by threatening publication of the book.

When he does drop names, we get the startling revelation that Crofts was a prospective Boswell to both the Marcoses and the Mubaraks, although respective revolutions in the Philippines and Egypt prevented anything reaching the shelf. Flirtations with such work inevitably raise the question – the subject of Robert Harris’s novel The Ghost, which was partly inspired by Crofts’s career – of whether the life-assister needs to approve of the life. With impressive candour, he admits that he might well have been tempted, journalistically, not politically, by an offer to co-operate on Mein Kampf. Ghosting can open doors closed to reporters and diplomats.

As Confessions of a Ghostwriter is an example of the ventriloquist chucking aside the doll and delivering a monologue, unusual attention is focused on the authorial voice. On this evidence, that voice is bluffly clubbable – publishers are “such august folk”; a book “has sailed out into the world” – but culturally intelligent. Intriguingly, Crofts identifies The Great Gatsby’s Nick Carraway and Charles Ryder of Brideshead Revisited, voyeuristic plodders who seek access to great houses, as prototypes of ghostwriters.

I turned next to Joey Essex’s Being Reem (a spectral bestseller), which represents an unusually severe test for the memoir form, as the subject became famous for inarticulacy and a lack of self-knowledge, or indeed of much knowledge at all, having once on television mixed up Jesus Christ and Guy Fawkes. But the acknowledgements page makes unexpectedly compelling reading. “Firstly,” Essex notes, “I’d like to thank Lucie Cave for helping me turn my life into words you can read and enjoy. I don’t know why she’s called a ghostwriter, she’s not actually a ghost, she’s a real person!” The tone of moronic bonhomie passes the first test of assisted life-writing – it certainly sounds like Joey.

Haunted canvas

Another type of literary ghost is the image of a writer stamped upon pos­terity through the portraits chosen for the cover of biographies. Hermione Lee’s life of Virginia Woolf nodded to the subject’s modernism by opting for a 1925 Vogue photograph, while Alexandra Harris’s biography went, more conventionally, for a Roger Fry painting.

Originals of both can be seen in the thoughtful exhibition “Virginia Woolf: Art, Life and Vision” at the National Portrait Gallery, among other less familiar images, such as a 1924 Lady Ottoline Morrell photo of T S Eliot and Woolf sitting in front of a fireplace, staring at the camera with expressions of such solemn apprehension that they resemble a couple about to receive marriage counselling from the Spanish Inquisition.

In almost every other image – by Morrell or anyone else – Woolf is sideways on: Man Ray and Gisèle Freund photograph her in such severe profile that her sharp nose seems to be trying to trim the margin of the print. Vanessa Bell, though, paints Virginia front on and softens and broadens the face. An act of sisterly kindness, I suspect.

“Confessions of a Ghostwriter” is published by the Friday Project on 14 August

“Virginia Woolf: Art, Life and Vision” is at the National Portrait Gallery, London WC2, until 26 October