Sir Arthur Conan Doyle - Inscribed Boer War Photograph

Original 87x87mm. square photograph of Conan Doyle standing in a trench/hole and inscribed on the verso "With all Xmas Greetings from the Waterval Prisoner's tunnel, A Conan Doyle". There is a 10x4mm. abrasion at the top right margin of the image which is otherwise in very good state. Of interest is that there is another copy of the same photograph with a slightly different Xmas inscription, being currently offered by a top London dealer at a substantially higher price than my reserve. How many of these photographs inscribed by Conan Doyle and used as a Xmas greeting is open to conjecture but this and the copy referred to above are the only ones I have ever come across on the market.