|[click to enlarge]|
The relevant 20th-century details of the Baltimore leaves are as follows:
- 1903: Henry Walters bought the leaves from the dealer Léon Gruel in Paris.
- 1931: Hanns Swarzenski recognised them for what they are (he had doubtless recently read Sydney Cockerell's monograph on de Brailes, published the previous year). 
- 1934: Dorothy Miner became keeper of manuscripts at the recently established Walters Art Gallery.
- Early 1937: she sent photographs to Sydney Cockerell for his opinion.
- March 1937: Cockerell replied, confirming Swarzenski's attribution to de Brailes.
- 13 October 1937: Cockerell was in Paris, and visited Léon Gruel .
- 15 October 1937: Cockerell wrote to Dorothy Miner and reported that Gruel said that he purchased the leaves loose at the Hôtel Drouot, the Paris auction rooms, "about forty years previously".
We now turn to the Wildenstein leaves. They were unknown until Eric Millar published them in 1939.  He provided no provenance, and to the best of my knowledge, no provenance has been discovered since then.
The auction of Manuscrits et miniatures ... composant la collection de M. P. Gélis-Didot was held in Paris at the Hôtel Drouot in April 1897:
"Creation de la femme. – Adam et Eve chassés du paradis. – Dieu vêtant Adam et Ève. – Repas d'Abraham et des trois Anges. – Joseph vendu par ses frères. – Miracle de Möise devant le roi Pharaon. ... Elles sont toutes, sauf la dernière, peintes sur fonds d'or qualdrillés, losangés ou diaprés."The subjects and sequence of these scenes, as well as their dimensions and the description of their tooled gold backgrounds, correspond to the set of six framed miniatures in the Wildenstein Collection shown here, and in colour at the top of this post:
The Wildenstein collection includes a seventh miniature from the same series, depicting Lot and the Angels:
Léon Gruel's memory may have been imperfect when he recalled, about 40 years after the event, that he had bought the Baltimore leaves at the Hôtel Drouot c.1897: the exact coincidence of date suggests that he may have been confusing them with the six Wildenstein miniatures, which (we now know) were definitely sold at the Hôtel Drouot in that year. Or perhaps both groups of leaves surfaced on the Paris market within a few years of each other?
I am confident that Gruel's source for the Baltimore leaves will also be identifiable in due course; we probably only need to search for them in exactly the place that he suggested we should look.
 W.G. Noel, The Oxford Bible Pictures (Faksimile Verlag, Luzern and The Walters Art Museum, 2004), with references to older literature.
 S.C. Cockerell, The Work of W. de Brailes (1930).
 Cockerell went on holiday in France for nearly four weeks from 21 September to 15 October 1937, apparently partly in order to avoid being in Cambridge (or even England) in the weeks adjacent to 30 September, the last official day of his Directorship of the Fitzwilliam Museum. In his diary for 1937 (BL, Add. MS 52675), his entry for Wednesday, 13 October, when he was in Paris, includes:
"had a good talk with M. Gruel, the only survivor of the booksellers of 30 years ago -- he showed me some good MSS and a volume of photographs of very fine MSS that he had sold to the Walters Collection at Baltimore"He left Paris the following day, and France the day after that, arriving home on Friday 15th October; and among the list of people to whom he wrote letters the day of his return is "Dorothy".
 E.G. Millar, "Additional Miniatures by W. de Brailes", Journal of the Walters Art Gallery 2 (1939), pp. 106-9.