This is the pre-1911 'Travelling-Primus' counterpart of the fixed-leg No.4 stove, absolutely nothing to do with the much later 1930s/'40s 'Primus No.10'. This Primus No.10 appears in the 1903 and 1905 catalogues, but is no-longer listed by the time of the 1912 catalogue. This specific example I would guestimate to be c.1905/8 as it still has old form of pressure pump assembly, and 'Patent' filler and pump caps, unlike this gallery example of the No.9 stablemate which itself is still pre-1911. On the other hand it does share with that No.9 a hexagonal riser base rather than the wingnut form (which was shown in the earliest catalogue entry for the model in 1903 but not in that for 1905). Yet another example of one of those really very old stoves that never seems to have had that much use.