Henry Ernest Dudeney/Modern Puzzles/2 - Pocket-money

by : $2$

 * Pocket-money
 * I went down the street with a certain amount of money in my pocket,
 * and when I returned home I discovered that I had spent just half of it,
 * and that I now had just as many shillings as I previously had pounds,
 * and half as many pounds as I then had shillings.
 * How much money had I spent?

Also see

 * Dollars and Cents, which follows exactly the same pattern.