
The Oratory dates from about April 1879.
It is catalogued in MacDonald 1995 (cat. rais.) [more] (cat. no. 716).

The Oratory, whereabouts unknown
Pennell's notes suggest the subject of Whistler's drawing was a building with pillars, and possibly a dome, in the classical style. There are two extant drawings answering that description (see St Paul's m1018) but neither could date from the late 1870s.
Brompton Oratory, Kensington, London. In April 1879 the Duke of Norfolk gave money for the establishment of the new Brompton Oratory in Kensington. H. Gribble designed the High Victorian Baroque building that resulted.
Unknown.
According to the Pennells,
'Whistler, one day when the talk was of the Oratory and what it ought to be, made a sketch of his idea for it. The sketch was thrown aside ... Then a fearfully hard-up moment came for all the group... Howell said he would see what he could do, the sketch suddenly reappeared, he carried it to Attenborough, the pawn-broker, returning with more money than any of them had ever yet pawned their work for. Time went on , the sketch was not redeemed, was altogether forgotten, until Whistler, passing Attenborough's, discovered it in the window, described as Michael Angelo's first drawing for St. Peter's, with a huge price tagged on to it.' 1
The Pennells told this story as coming from Whistler, but dated it 22 October 1906 (possibly meaning 1900). They apparently heard a variation of the story, citing Robert Baldwin Ross (1869-1918) as the authority, that 'the drawing had become one of the Louvre by Whistler which Jo tried to sell to Sir Sidney Colvin for the British Museum as a sketch of the Parthenon by Michael Angelo.' Joanna Hiffernan (b. ca 1843-d.1886) was in contact with Whistler for over 20 years, and indeed, had power of attorney while he was away in South America. She had every opportunity to acquire drawings by Whistler but is highly unlikely to have tried to sell such a drawing to Sidney Colvin (1845-1927).
It was not exhibited in Whistler's lifetime.
1: Pennell 1921C [more], pp. 63-64.