The Isons' great achievement was the book The Georgian Buildings of Bath, published in 1948. Walter Ison was the author and Leonora drew the illustrations. The measured, reticent facades of Georgian Bath are enlivened by occasional bursts of ornament and likewise his precise and elegant text is interspersed with her "decorations": sketches of doorways and gateways, of a monument or of the riverside grotto in which the playwright Sheridan is said to have wooed Miss Linley. The Isons shared and discussed their perceptions and sympathies throughout the book and The Georgian Buildings of Bath should be seen as a joint production.
In the 48 years since the book first appeared there has been a steady flow of publications on Bath's architectural heritage. Placed side by side, these now fill two metres of shelving in the city's branch of Waterstone's, but if one were to add together their worthwhile content it would amount to less than that of the Isons' single volume.
The thoroughness of the research into primary sources has made the book resistant to academic revisionism. Its endurance is also owed to the authors' discretion: they did not clutter the reader's view of the building with personal impressions. We do not read of "honey-coloured stone dripping with sunlight" or "ringing cobbles", phrases which are the stock-in-trade of the writer on Bath. None the less, the book is founded on a passionate enthusiasm expressed in the introductory declaration: "Bath is, beyond any question, the loveliest of English cities."
The Isons had fallen in love with Bath and Walter Ison discussed the book idea when he was working in the RAF's secret model-making section at Medmenham in Buckinghamshire during the Second World War. It was Leonora who made the book happen, by devoting to the project a legacy which she had received; at this time little or no funding was available for long research into dusty, uncatalogued archives.
Immediately after the war they had moved to No 5 Sion Hill Place, Bath, the central house in a Regency terrace. This was a time when Bath's Georgian building stock was neglected and black with soot; a dilapidated house on Royal Crescent could be had for less than pounds 2,000 and hundreds of town houses were sub-divided into squalid, unheated bedsits.
By the time the book's third edition appeared in 1980 the tide of demolition and decay had been reversed. It is impossible to say how much this was due to the Isons, but in many of the campaigns and public enquiries fought by Bath Preservation Trust the book's research provided a pedestal of authority which no developer could overturn. Bath Preservation Trust has recently reprinted the book, partly as a gesture of gratitude.
In 1952 the Isons published The Georgian Buildings of Bristol and Leonora was also to provide illustrations for Walter's English Architecture through the Ages (1965) and English Church Architecture (1972). In the 1960s she began to illustrate John Betjeman's articles in the Daily Telegraph on "Men and Buildings". Many Telegraph readers requested copies of the drawings and in Betjeman Country (1983), Frank Delaney wrote: "Mrs Ison captured Betjeman country in its heyday, at a time when he was most prolific, in the 1950s and 1960s, and echoed the world as he saw it, a sort of visualising amanuensis." Walter Ison remains proudest, however, of the admiration of Sir John Summerson, the great and inimitable writer and historian, who had been a fellow student of hers at the Bartlett School of Architecture and first discussed commissioning her illustrations for his 1935 book on John Nash.
Leonora Ison was born at Wendover in the Chilterns in 1904. Her father Edward Payne, who died that year, was a barrister and historian and Recorder of Wycombe from 1883. (Her brother Humfry, the archaeologist, was Director of the British School at Athens until his early death in 1936.) She was educated at St Paul's School for Girls before attending the Bartlett, where "she was one of several outstanding women students who proved their worth by winning prizes", according to Lynn Walker, the historian of early women practitioners of architecture. In 1926, her final year at the Bartlett, she won the Owen Jones Travelling Scholarship and was the first woman to do so.
She worked for the cinema architect Frank Verity, father of the sculptor Simon Verity, in whose office Walter Ison worked as an architectural assistant. They married in 1931, retired to St Leonard's-on-Sea, and were inseparable until her death 65 years later.
Leonora Florence Mary Payne, illustrator: born Wendover, Buckinghamshire 4 July 1904; married 1931 Walter Ison; died St Leonard's-on-Sea, East Sussex 21 November 1996.