London is 4 hours ahead of San Juan during standard time. San Juan uses Atlantic Standard Time (AST, UTC-4) year-round while London uses Greenwich Mean Time (GMT, UTC+0). When it's 12:00 PM in San Juan, it's 4:00 PM in London.
Puerto Rico does not observe daylight saving time. During British Summer Time (BST), the difference increases to 5 hours as London moves to UTC+1.
Best calling time: 8:00 AM - 12:00 PM San Juan time. This corresponds to 12:00 PM - 4:00 PM in London (or 1:00 PM - 5:00 PM during BST), covering UK afternoon business hours.
San Juan and London have historical connections through Caribbean trade. The UK has a growing tourism interest in Puerto Rico, and British visitors appreciate the blend of Caribbean and American culture.