Cyril Tawney was the guest at my local club, Folk on the Moor, Wotter. Someone had pointed me out to him as a fellow ex-submariner and he'd come across for a chat. We talked submarines for a while, lovely man as I'm sure you all know. He made a point of singing Diesel and Shale (which was something of an anthem to submariners in diesel boats). Then, during the interval, he came up to me and asked "'ere Andy, what exactly was shale?"

I'll never know if he was testing me, had forgotten or genuinely never knew. We were both in the electrical branch (two or three decades apart, I hasten to add), so were above such mundane things as oil.

(For those who must know these things: shale oil was,apparently a light lubricant and preservative by oil used in subamrines. It was replaced by an oil with a NATO designation letter and number...much harder to fit in a song I should think.)