This is one of those cases where the answer is "it depends".
Items procured via QMG "Stores" were usually introduced as a "mark". This is particulary true for items in the late 19th C through the First World War. However, this is not 100% for all cases, some items such as groundsheets found the "Mark" designations applied retroactively.
So I don't think I gave you the answer you wanted.
Telescopes were under QMG "Stores"--"Stores" being an unofficial designation of Quartermaster General's Branch 9 of the The Directorate of Equipment and Ordnance Stores.
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