Following British Airways' decision to retire its Vickers Viscount turboprop fleet and to withdraw from its loss-making regional scheduled routes, Air UK assumed BA's regional routes from Heathrow to Guernsey, Manchester to the Isle of Man, Leeds to Belfast and Dublin, and Edinburgh to Jersey in April 1980. Air UK's new, year-round Heathrow—Guernsey route was its most prominent scheduled route serving London's premier airport. (During the late 1970s, in the days prior to the construction of the M11, Air UK's predecessor Air Anglia had launched a year-round scheduled service linking Heathrow with the company's bases in Norwich and Humberside, as well as a year-round scheduled operation between London Gatwick and Leeds.)