[7] Roddy Simpson has written of McCosh's photographs that "Given the circumstances, these images are a considerable achievement and, regardless of artistic merit, are historically very important".
[8] Taylor and Schaaf have written that "McCosh fashioned compositions that were exceptional for the period"[3]: 123 and that unlike his contemporaries "in his hands, photography was not merely a pastime but became the means of recording history.
[9] On 11 October 1833, on sick leave with a tropical disease, the barque on which he was sailing from Madras to Hobart in Tasmania, Australia,[n 1] was wrecked off the desolate and remote Amsterdam Island in the southern Indian Ocean.
[2] In 1843 McCosh returned to India as assistant surgeon with the 31st Bengal Native Infantry, taking part in the Gwalior campaign and its battle of Maharajpur on 29 December 1843.
Mostly his photographs were portraits of fellow officers, key figures from the campaigns,[4] administrators and their wives and daughters, including Patrick Alexander Vans Agnew,[2]: 911 Hugh Gough, 1st Viscount Gough; the British commander General Sir Charles James Napier; and Dewan Mulraj / Mul Raj, the Diwan (governor) of the city of Multan (a key leader of the Sikh nation against the British).
A stone to his memory stands on the north wall of the first northern extension to Dean Cemetery in west Edinburgh, where his siblings are buried.
Roddy Simpson, in The Photography of Victorian Scotland (2012), wrote of McCosh that "these photographs do not have significant aesthetic quality, but show the desire to document likenesses.
[8] Taylor and Schaaf, in Impressed by Light: British Photographs from Paper Negatives, 1840–1860, wrote that "McCosh fashioned compositions that were exceptional for the period"[3]: 123 and that unlike his contemporaries "in his hands, photography was not merely a pastime, but became the means of recording history.
"[3]: 123 Taylor and Schaaf have also written that "the kind of work done by McCosh, [John] Murray and [Linnaeus] Tripe was echoed in a wide pattern of photographic activity throughout India, and in many ways, these three can be regarded as role models to whom others looked for inspiration."
... "Few photographers in the calotype era came close to matching the sustained output of these three, and in visual sensitivity and technical bravado they remain unequalled.