[turretslug]

As well as improved-safety bayonet lamp-holders, ES types have also improved in recent years with the outer contact being formed by a narrow crescent at the bottom of the base well that's isolated from the metallic threaded ring. Of course, they are connected together by the action of fully screwing-in the bulb but there's generally enough of a flared plastic collar on modern types to make accidental contact much less likely.

Both types are classic examples of legacy designs that, if someone invented then tomorrow, the approval authorities would say, "Go away, and try harder" but we're stuck with these late-Victorian fitments. To be fair, they do their job pretty well and have at least been adaptable to increase in safety concern and awareness.