Green’s Dictionary of Slang

Lady Blamey n.

[Lady Blamey, widow of Sir Henry Blamey (1884–1951), who taught soldiers how to cut a beer bottle in two by winding a kerosene-soaked string around it, setting the string alight and then plunging the bottle into cold water, where it broke cleanly; however, note Smith’s Wkly (1941) gives a more seditous (and thus more feasible) origin]

(Aus.) a drinking vessel made of half a beer bottle with the cut edge rounded by sandpaper.

Show quotations
[Aus]Smith’s Wkly (Sydney) 13 Sept. 3/6: Returning troops say that ‘a Lady Blamey’ Is already known throughout the length and breadth of Palestine. Troops say that an order was issued by General Blarney to the effect that, as Australian troops wore able to buy too much beer in their canteens, he directed that the beer bottles be cut in halves, and the lower half used as a measurement and a glass. [...] Returned men say they gave these rough beer pots the name ‘Lady Blamey’ because the Australian Government didn’t authorise their presence in the Middle East any more than it did Lady Blamey’s.
[Aus]West Australian (Perth) 27 Jan. 3/6: [A]fter tea each thirsty O[ther] R[ank] grabs his Lady Blamey (the cut-down bottle which, for inscrutable reasons, has conferred on the C-in-C’s wife a glorious immortality) and races to the beer queue.
(ref. to 1942–3) Harold’s War 🌐 You found an empty beer bottle, and there was no shortage of those, as all bottles regardless of the brewer were identical, found a piece of string, soaked it in methylated spirits, tied it around the bottle just below where it commences to slope in to the top, light it. At the right time plunge the top of the bottle into cold water, and the top breaks off and leaves a smooth edge, and you have your own beer glass. If you pushed hard enough at an overcrowded bar, and it so happened the pub still has some beer, you got a drink. These ‘glasses’ were called ‘Lady Blamey’s’ after the wife of our top General.