§ Mr. Letwin
To ask the Secretary of State for Foreign and Commonwealth Affairs what mechanisms Her528W Majesty's Government uses to police the sale of arms by UK-based companies under circumstances where those arms do not touch United Kingdom soil. 
§ Mr. Tony Lloyd
The Import, Export and Customs Powers (Defence) Act 1939 gives the Government power to control only exports from and imports to the UK. As such, it does not allow the Government to impose controls on the involvement of persons in the UK or UK persons abroad in trafficking in goods between overseas countries or in brokering such deals. However, the Government do have the power to control trafficking and brokering under the United Nations Act 1946 where this is necessary to implement a binding UN decision, such as a binding UN arms embargo. The DTI White Paper on Strategic Export Controls (Cm 3989) contains a proposal to introduce a power so that the Government can also control the involvement of persons in the UK or UK persons abroad in trafficking and brokering in controlled goods to countries which are the subject of other types of embargo, such as those resulting from decisions of the EU, OSCE or the Government; in certain types of equipment, the export of which has been banned from the UK because of evidence that goods of the same type have been used in torture; and in missiles capable of a range of at least 300 km. The White Paper's proposals relating to weapons of mass destruction also cover trafficking and brokering.
The investigation and prosecution of any alleged breaches of UK legislation implementing UN embargoes or sanctions is a matter for the Commissioners of Customs and Excise.