"some northern dialects have used 'dollar' for 'pound' for a long, long time"
When I were a lad in t' Dales, we called a crown (5/-) a dollar. Or, more usual, a half-crown (2/6) was half a dollar (and the cost of a Pint when I first got to Yorkshire). Later, I remember Reg Smythe's Andy Capp calling 50p a dollar. Now it's a pound. Must be inflation.