This is also why the symbol for a British pound Sterling is a stylised "L".

Edit: the currency was at one time backed by silver, so 1 GBP used to be = 1 lbs silver.

Similarly...Americans size wire carpentry nails as some number followed by a d. 16d nails are most common for nailing together two-by lumber as standard in structures, 8d are used for one-by lumber trim or plywood.

The d is pronounced 'penny'. And like most of the stupid little stuff we do, it's the Limeys' fault.

Back when the UK had three moneys rather than two, they abbreviated pound as L (as above), shilling as S and, for some crumpet eating reason, pence as d. At some point in history, nails were sold in lots of 100, and different sizes at different prices. A box of large framing nails might cost 16 pence, a box of small tacks might cost 4 pence. The terminology has pretty much stuck to this day.