Declaration to customs is required at UK arrivals and departures when a passenger is carrying 10,000 Euro or more between a non-EU country and the UK (including cheques and traveler's cheques).(As of June 15, 2007)
Declarations Forms can be obtained from the UK arrival or destination airport, or can be downloaded from the HMRC (HM Revenue & Customs) website. Declarations Forms are not carried in the aircraft.
Failure to declare cash will result in a fine of up to ₤5000.
For more information, please refer to the Government News Network.