Found in a botanic garden in France, this iris could be a variety of things and is particularly hard to identify confidently. All the same, there are strong indications to suggest that it is Camelot. (It was listed in the garden a few years earlier,) and the claw shows the olive colour suggested in one description.
TB-M-W2 (AIS checklist 1939: superseded?)
Assuerus x Mrs Horace Darwin
Habit and foliage like Ma Mie but foliage 24" [60cm] high. Flower stem 32"[80cm], 8 flowered. Flowers small, close well proportioned, stiff. Standards waved 1¾"x 1⅞", margins waved veined and suffused lavender. Falls sigmoid and tucking back, 1¾" x 1⅜" margins feathered lavender. Crest lavender, beard tipped orange. (paler + redder than Ma Mie)( RHS trials, Wisley: 1925-27)
The large branching of Camelot bears flowers having a creamy white ground, faintly suffused with blue at edges of falls and more blue in standards. The flower is rather unique as it fades with age to almost cream white. (Gardeners Chronicle: 1919)