[holding answer 12 March 2007]: The weighted-capitation formula, used to inform revenue allocations to primary care trusts (PCTs), does not take specific account of detainees in Immigration Service removal centres. However, migration is taken account of within the population base used for revenue allocations. The population base is a combination of Office for National Statistics (ONS) populations and general practitioners lists. ONS add asylum seekers to their population estimates using data provided by the Home Office. All removal centres have primary healthcare provision on site. National health service services are only used, therefore, when detainees cannot be treated within the on-site Home Office funded primary care services.