Though it takes a bit of a spill in The Reichenbach Fall, the
distinctive mug the warden of Pentonville Prison enjoys drinking
his favourite beverage from is thankfully shatterproof. A
traditional tin mug protected by an enamel coating, the slogan on
the side was designed in 1939 but never widely used as morale
boosting propaganda for the British population during the Second
World War. A copy of the poster was rediscovered in a bookshop in
Northumberland, UK, in 2000, and thanks to the elapsed time was
exempt from Crown Copyright and was thus in the public domain. It
has been reprinted on a vast variety of products ever since, and
has been spoofed and re-imagined in countless other media and
cultural sources.
Though the mug seen onscreen in The Reichenbach Fall is in black
font, the mug is more commonly available in a red font - if you
aren't overly fussy and just wish to live up to that steadfast
British spirit.