A small estate called Friars in North Wales was purchased by Saunders-Roe to become a base for the works to modify the newly delivered Catalina aircraft from the USA to the standards required for Coastal Command. An area offshore, to the east of the suspension bridge across Menai Straits, was chosen, as it was able to provide a sheltered deep water-landing zone. Saunders Roe dismantled one of their spare T hangars at Cowes and re-erected it on the site in August 1941. The Ministry of Aircraft Production built a T2 hangar and workshops on the site in December 1941 and linked to the foreshore by a concrete slipway, Friar’s House also became part of the factory complex. The slipways and the hangars that were built are still present but no access is permitted onto the site due to the structural condition and dilapidation of the remaining buildings.
Over 300 planes had armament installed, including .303 Browning machine-guns and British type bomb-racks (to carry up to 12,000lbs), plus radio equipment, Air-to-Surface Vessel radar (ASV) and Leigh Lights. The first Catalina arrived in April 1941 and over 300 Catalinas passed through Saunders Roes new facility for conversion throughout the war.