"Origins of words" by Susie Dent, Countdown 20/10/17 (swinging the lead, marine)

I don't suppose anyone's ever accused you of swinging the lead. I think probably not. But if they had, they would've been accusing you of being a sriker basically, a lazy malingerer, and the British idiom, definitely British, it's first founded in the Army slang, so during the First World War, but it probably came onshore via the vital Naval activity which is depth sounding, so measuring the depth of water in which a ship stands or floats, if you like. So masuring between the ship and the seabed or river bottom. And these were in the days before sonar transformed the entire exercise. Soa lead was a very large lump of lead that was suspended from a rope and that was known in full as a lead line, and it was lobbed from the side by the leadsman and it came to reat on the seabed. And it had markers, knots, or different sort of measurements, if you like, so that the leadsmen could gauge just how far the ship was from the sea bottom and it would ensure, of course, that the vessel didn't run aground, which was incredibly important. That lead was incredibly heavy, so it could weight anything from 9 lb to 32 lb. So particularly in rough weather, if you can imagine, that was a pretty demanding task. So that all seems a bit puzzling. Why then did such a difficult task come to mean something that involved, you know, somebody being lazy, basically. Well, it's probably because in some cases, the leadsman, instead of dropping the weight right to the seabed, would shrink his duty and just swing it over the side and then sort of happily sit there, if you like, without giving the exact measurement. But more likely the meaning stemmed from the rivalries, traditional rivalry between the Army and the Navy, because when I had to research my book, and I spoke with sailors and soldiers, they had such joking acronyms for ewach other and the ones that the Army insists on for any marine is that "marine" itself is an acronym for Muscles Are Required, Intelligence Not Expected. So, swinging the lead, yes, something you,ve never, never done, but it's a really good expression, I think, for somebody, who's just really bunking off and not pulling their weight.