One possibility for part of the collection at Lancaster House in 1931 is this piece by Sir Joshua Reynolds entitled: Colonel Acland and Lord Sydney: The Archers.
It was created in the late 1700s and was sold in 2005 for £2.5 million.
Dimensions: 238.7 cm × 184.2 cm (94.0 in × 72.5 in)
Another option is for Watson and the Shark, which has the added link to Portia that I like, but less of an ability to easily play with the title (more cryptic than I mean it to be, but I don’t want to give away the premise of the first chapter of the book – sorry!).
This oil painting came from the same era exactly, but was painted by John Singleton Copley. The vertical copy of this piece is now in the National Gallery of Art in Washington D.C. It was sold off in 1963.
Dimensions 182.1 cm × 229.7 cm (71¾ in × 90½ in)
Problematic for a few reasons: it never seemed to make it into the London Museum (and therefore never made it to Lancaster House), there are three copies, making it less valuable and like I stated earlier, the title is harder to work with.
An additional piece that I could relate to the first painting above is the bronze statue of Apollo from the ruins of Pompeii. The following text and image is from getty.edu: “In June 1817 the majority of the Apollo, broken into three pieces, was found just north of the forum in Pompeii, not far from the Temple of Jupiter … its reconstruction was complete by 1825.”
So if this could have been in the collection at Lancaster House (which I suppose it could have been, on loan from some museum in Italy I have been unable to find so far) then this could mesh nicely with the kernel of a story I have in my head.
Dimensions: 147 (h) x 55 x 114 (d) cm
I’d like to know the weight of this statue, but have been so far unable to find that.