Greenwich 2000 has a list of the world's time zones through its website, greenwichmeantime.com. The difference in hours shown is based on the time at the Royal Greenwich Observatory in Greenwich, England, which is at zero degrees longitude.
Ireland, Portugal, and the Canary Islands share the same time as the United Kingdom. Hours are subtracted from GMT as time zones move west of the International Date Line. Noon in London, England, would be 7 a.m. in New York and 4 a.m. in Los Angeles. Time zones east of GMT add hours. Noon in London would be 1 p.m. in Paris, France, 3 p.m. in Baghdad, Iraq, and 9 p.m. in Tokyo, Japan.