belM

What you interpreted (cleverly) as LSD, are actually the symbols for currency in the UK, pre-1970: £(Pounds), s (Shillings) and d(Pence - from denarii, don't ask, we were very influenced by the Romans). The reason why Rhuby is proud of his ability to use it is not because he was hippy-trippy in the '60s (though he may well have been - given the tale of his car and its decorations), but because the currency, not being decimal, was virtually impossible to calculate in - almost as bad as doing multiplication and division in Roman Numerals.

cheer

the sunshine (glad to have lived primarily in decimal times) warrior