Romanophilia, a passion for the way of the Romani gypsy, survived the rest of the Romantic movement and lasted well into this century.

"Like nature herself," wrote George Hall, one of the many minor eccentrics in Anthony Sampson's peculiar memoir, "these wildings of hers overflow with the play-spirit and therefore remain ever youthful." Hall, a Lincolnshire rector, wrote this in 1915, the same year he fell, drunk, out of a wagon in North Wales and found himself amidst a group of sympathetic souls who studied and sported with the local gypsies. The rationale for this bizarre field studies centre was the Wood family, gypsies who spoke the "deep" Romani language. Their discovery had motivated the librarian of Liverpool University to move his household to the little village of Bettws-Gwerfil-Goch in order to research the dictionary of Romani he was compiling and would eventually publish in 1926. He was John Sampson, known as `the Rai" to gypsies and a circle of friends who ranged from the painter Augustus John and the poet Arthur Symons to philologists such as Kuno Meyer, a German pioneer of Celtic Studies.Not quite as whimsical as Hall, one might suppose, the Rai's linguistic enthusiasms had an intensity all of their own. A friend met him on his way to the pub with two gypsies already speaking Romani in high spirits. "Suddenly Sampson seemed to be overcome by an intense emotion: he stopped dead and bawled out . . .: `Oh, Davies! did you hear him use the ablative - how perfectly beautiful!'."Such eccentric charms are scattered through Anthony Sampson's biography of his grandfather, but the gradual revelation of the Rai's private life makes the Rev Hall a model of restraint by comparison. As a child Sampson Junior was fascinated by the dark reputation his family gave the Rai. As a student he began to appreciate the scale of his grandfather's academic achievements. Now, with his own pedigree as a liberal journalist and writer solidly established (and perhaps as an off-beat warm-up for his current project, the authorised biography of Nelson Mandela), Anthony Sampson presents a portrait of his forebear as a bohemian pedant and a secret philanderer.A mysterious Aunt Mary, who became part of the Sampson family after the Rai's death in 1931, provided the impetus for deeper delving into family history. She is identified as an illegitimate daughter at an early stage, but the question of her mother's identity provides the whodunit element that takes the book through to its close. John Sampson enjoyed congress with more than one of his female research students at the university and, in all likelihood, with more than a few of the gypsies he studied so diligently.John Sampson's marriage buckled and finally, though privately, broke under the strain. Once located out in Wales, the family stayed there through the year while he was able to spend long periods in Liverpool, tending his library and students. "I don't want my work to turn me into an absolutely selfish and self-centred person and you must warn me if you see this coming on," he wrote to his wife Margaret in 1914.It had, of course, already come on. At least such monumental selfishness produced a monument, The Dialect of the Gypsies of Wales. One reviewer called it a "narrative of the Gypsies' long and leisurely walk from India to Wales". While the dictionary will remain an obscure if exotic memoir of a nearly dead tongue, the making of it may well have helped the gypsies in their centuries-long battle against persecution. If they appreciated his dedication to their origins, they also had a clear idea where he was coming from himself. Anthony Sampson managed to track down several members of the Wood family, still proud of their Romani blood.

Reubena Wood, now in her 80s, said her father, who had helped the Rai with his vocabulary, had admired him, but "thought he was after my mum".Charles Hunter is a journalist and critic