'Thrush' was a British operation by the Special Operations Executive to establish a radio base in the Bykle district of German-occupied southern Norway and also to arrange for the receipt of stores and equipment for the 'Cheese' area (25 November 1942/February 1943).

B. Fjelstad and N. Gabrielsen were parachuted into Norway during the night of 25/26 November. Fjelstad was to contact the local resistance leadership and act as an arms instructor. He was also to establish a radio station, which came on air on 7 December, and reconnoitre landing places for the 'Carhampton' operation. In December many resistance fighters were seized, and in February 1943 both Fjelstad and Gabrielsen escaped to neutral Sweden.