It's a lot easier to run lamps vertically (or in any position) since we acquired the laboratory retort stands.

Nice lamp . I got cheated out of a Westinghouse version a few years ago .

Any particular reason why the lamp was operated cap up? Given the electrode configuration, I'd say this particular lamp was optimized to be burned cap down (but I may be mistaken).

You are very rarely mistaken Max, that's just the position that the manufacturer specified.

Interesting, I'd have placed the end seals with the most heat losses on top rather than at the bottom. Thanks for this bit of trivia.

Is there no start resistor and electrode in this lamp or is it just hidden by the camera angle

It's there, those elements are at the bottom of the lamp where temperature is the lowest when burned as shown - hence my initial question given the risk of mercury condensation there.

I checked the literature and GEC does indicate that "MA/V lamps are intended for operation in the cap-up position. Special types are available for cap-down burning." (Osram lamps and tubes, 1955, p.35) without pointing to any other lamp reference. So, it is clear that they had distinct MA/V lamp designs for cap up and cap down operations, and given that Sammi's lamp is the only one I've see with the resistor and the starting probe on the end side of the lamp (i.e., opposite to the cap), clearly a special design, then it is most likely that the lamp shown here is the rarer cap-down version of the MA/V!

I believe that in British nomenclature, /V stands for vertical cap up only. For cap down operation, the suffix is /D so an MA lamp intended for cap down operation would be MA/D. This lamp is marked MA/V.

As an example, here is an MB/D lamp.

Probably true as far as the general British nomenclature is concerned, but GEC certainly did not use the MA/D reference in the catalogs I checked. When was your lamp made by the way?

Not sure off hand, will have to find it and check, watch this space..!