The total number of UK personnel visiting the Nevada test site under the auspices of the joint United Kingdom/United States Mutual Defence Agreement (MDA) is provided in the following table.
Number 2002 27 2003 62 2004 30 2005 89 2006 53 2007 58 2008 91
These figures include personnel making more than one visit in any given year.
Two specific sub-critical plutonium experiments were conducted in 2002 and 2006, the purpose of which was to gather scientific data essential for the maintenance and reliability of both US and UK nuclear weapons without having to conduct underground nuclear tests. The increased activity in 2005 coincides with preparations for the second of these experiments.
The increased activity in 2008 reflects a number of unrelated visits associated with stockpile maintenance activities and a specific classified project relating to nuclear counter-terrorism, details of which I am withholding in the interests of national security.
In addition to these visits, a number of other non-MDA related visits will have taken place. Statistics covering these visits are not centrally held and could be provided only at disproportionate cost.