In her mid-fifties now, tall, angular, hair faintly badgerish, Faith Spurgeon belongs to what these days is a highly exclusive part of the social demographic: the downwardly mobile, aristocratic poor.

Her grandfather was a peer of the realm who lost most of his money in the Wilson-era property crash. Her father, a semi-professional poker player whose name can sometimes be found in the indexes of books about Lord Lucan, squandered the rest in the card rooms of a succession of gentleman's clubs, and by the late 1970s there was only just enough capital left to send Faith, his only daughter, to Oxford.

Everything would have been fine if only Faith could have married her way into financial security. Sadly, in Jonty Spurgeon, formerly of the Blues and Royals, then Cazenove's, the royal stockbroker, she picked what her father – when hanging around the paddock at Newmarket race course – would have called the worst horse in the field. When Jonty died in his early forties, of an unsuspected aneurysm, having been sacked from Cazenove's and done little else afterwards, he left behind him only two blooming daughters and a four-bedroom house in Putney with an unsecured, interest-only mortgage of £125,000.

Noblesse, as ever, obliged and somehow the money was found to pay off the building society and send the Misses Spurgeon to St Paul's Girls School. But what was to be done with their mother, who had never, it turned out, had a proper job and lacked any of the technical or managerial skills thought necessary to succeed in the modern world of work? In the end, somewhat to the surprise of her relatives, Faith answered an ad in The Lady and obtained the post of matron at Bicester Ladies' College, a girls' boarding school in north Oxfordshire.

Fifteen years later, the experiment can only be judged a success. Respected by her headmistress, esteemed by her colleagues, "Spurgy", as the girls call her, is as much a fixture of the establishment as the statue of Lady Elvira Warburton, friend of Mrs Pankhurst, and the school's most prominent alumna. Her greatest ally is the cook, with whom she watches television soap operas in the evening. There is even talk of the pair of them retiring together to a cottage in Lincolnshire – a far cry from the country house in which she spent much of her childhood, but no less enticing for that.