There are those who might quake at another fat tome about the Brontes from prize-winning biographer Juliet Barker. Personally, I hope she pens dozens more - so long as she keeps up her remarkable line in Acknowledgements, which she has developed into an artform.

Lest anyone doubt the elbow grease and emotional turmoil that went into Barker's Bronte biography, the Acknowledgements paint a vibrant picture of rows at home, where "parents, husband and children" have "suffered endlessly (but not always in silence)". I may be wrong, but I believe that the acknowledgement "to Ian Beck, consultant gynaecologist and obstetrician, who saw me through the worst year of my existence" is a first in literary scholarship. The "one exception" to the "wholehearted assistance and support" Barker met was the Bronte society itself, whose "Director and Council felt it necessary for their own commercial reasons, to refuse permission for the reproduction of a carefully chosen selection of Bronte drawings... As a former employee and a Life Member of the Society I particularly deplore this action."

Her difficulties did not put Barker off producing a spin-off: this Life in Letters. Given that she had already consulted so much material, it would have been a shame not to follow up her success and print some sources. The problem is that none of her extracts is sourced - I am all too aware that what we have here is Barker giving us selected material that supports her own thesis. Anyone truly interested in the Brontes' letters would do better to acquire Muriel Spark's insightful essay on the subject. A glaring omission by Barker, for example, is the letter from the Bronte Mama to the Bronte Papa beginning "My dear saucy Pat". It both undermines preconceptions about dour Patrick Bronte, and reveals something of the literary genes inherited by the novelist children.

But the Acknowledgement here will not disappoint. We learn of Barker's incomparable nanny. Penguin Books are thanked for their "generously expressed confidence" (big cheque?). Pride of place goes to one who has "entertained and educated me - and left me begging for more." This is a certain "John Burgess of Raffles, Queensland grazier and kindred spirit". Who he? I think we should be told.

Despite claims from Barker's publishers that these tomes are "definitive", history reveals that she will not be the last. Every age has its Bronte interpreters: Mrs Gaskell, Winifred Gerin, Phyllis Bentley, Jane Sellars, Juliet Barker. Barker's Acknowledgements, though, are her unique contribution. Here you may detect all the skulduggery and intrigue that lurk in AS Byatt's brilliant take on literary scholarship, so aptly named Possession.

Viking, pounds 20