Nineteen Boeing-built B-17Fs were transferred to the RAF under Lend-Lease as Fortress II. They were assigned the RAF serial numbers FA695 to FA713. FA700 and FA711 were ex-USAAF 41-24599 and 42-5238, but I am unaware of the other USAAF serials.
Most Fortress IIs were issued to RAF Coastal Command for use in patrolling the area around the British Isles in search of German submarines. The Fortress II served with the following RAF Coastal Command squadrons:
No. 59 Squadron No. 206 Squadron No. 220 Squadron No. 251 Squadron (Met.) No. 519 Squadron (Met.) No. 521 Squadron (Met.)
The Fortress II also served in small numbers with the following RAF Bomber Command Squadrons:
No. 214 Squadron No. 223 Squadron