But this is -- simply observing where the oil is coming out is insufficient to really calculate any flow rate with any degree of accuracy.

WHITEHOUSE: Press Briefing on Oil Spill in Gulf of Mexico

Given that transitional controls were ending in eight other countries as well as the UK , he said the number of people who might opt to come to the UK could not be forecast with "any degree of accuracy" and the government's advisory body on immigration had recommended against it.

BBC: Airport arrivals sign