HuwG: of course a Tantalus is also a container (usually antique) containing decanters of liquid (usually spirits) which, although in full view, can only be unstoppered if the tantalus is unlocked. The derivation is the same.

bert: "How can an Englishman be a Tory if he has the slightest intelligence? "
With difficulty, if he has 'the slightest intelligence' he should vote Labour!
With normal, or greater intelligence then he may vote Conservative.

Nigel