According the Encyclopaedia of British Auction Catalogues p 224 there was a Sotheby's sale on 9th May 1913 of his collection by Doyle “who is confining his collection to classical types”

Conan Doyle's sale took place at Sotheby's (not Christie's), on 9 May 1913, as part of a very general auction of coins totalling 175 lots.

I have a copy of the catalogue by me as I write. The Conan Doyle property occupied just 22 lots. It comprised a few European gold coins, a very disparate run of English coins and a handful of Scottish (Conan Doyle was a Scotsman, so one would have expected that). Altogether the whole collection realised under 28 GBP (in today's values 2,850 GBP, or US $4,075 at this morning's exchange rate). Not a very exciting collection!

The cataloguer did say that Mr Conan Doyle "is confining his collection to classical types" – perhaps one of your subscribers knowledgeable in the field of classical coins knows what happened to them?

1) It was an auction of Sotheby, Wilkinson & Hodge, not Christies.

2) Cover: "Sotheby, Wilkison & Hodge / Wellington Street, Strand, London

Catalogue / of / COINS, TOKENS & MEDALS / the properties of / William Dash, Esq. of Kettering; / Sir Arthur Conan Doyla, / and other properties.

Day of Sale / Friday, the 9th of May / 1913"

3) Title Page: "[after Dash]...A small collection of / English and Foreign Coins, &c. / the property of Sir Arthur Conan Doyle. / ...[and other properties]

I.e. the Doyle coins are only a part of the sale, lots 68-89 out of a total of 175 lots. These 22 lots are a gathering of 421 coins, mostly not described and not worth describing. Scattered British from Anglo-Saxon to Charles II, some continental (gold of Charles VI and VII of France).

4) Our copy of the catalogue is annotated per lot as to price and purchaser. Only the penultimate lot 88 was properly classical, 4 dupondii of Faustina I and II, "appear to have formed part of a hoard". The ultimate lot 89 is a junk lot of 63 undescribed pieces, including some classical.

The 22 lots together brought just under £28, pretty unimportant stuff.

This information can be photocopied if anyone wants to know.

I have looked at two modern biographies and the recent collection of his letters and none mention coins.