HM Customs and Excise has now been merged with HM Inland Revenue to create HM Revenue & Customs but, as Loosehead states, they are still the people who deal with cigarette smuggling.
Illegal activity should be reported to HMRC, using their confidential hotline or the other contact methods given here:
http://customs.hmrc.gov.uk/channelsPortalWebAp p/channelsPortalWebApp.portal?_nfpb=true&_page Label=pageTravel_ShowContent&propertyType=docu ment&resetCT=true&id=HMCE_PROD_008211
Chris