Excellent source of travel. Many updated information for sights and theatres etc. Make sure the rate and commission before you change money. Earl's Court, just in front of the main gate. Good palce to change money.
Cash is higher for rate.
You don't have to go to telephone office. Local calls 10p. You can have international call or collect calls from most of the pay phones. But if you call overseas, you buy private company phone cards. They all use pin code system and call back system.