157 Squadron Royal Air Force formed on 14 July 1918 at RAF Upper Heyford and was eventually equipped with Sopwith TF.2 Salamander aircraft for ground support duties, but disbanded on 1 February 1919 without becoming operational.

The squadron flew patrols over East Anglia and by July 1943, after moving to RAF Hunsdon, began intruder attacks on German fighter bases with its new Mosquito Mk VIs.

In November 1943, it moved to RAF Predannack in Cornwall, closer to the German bases.

In March 194, it moved to RAF Valley and flew defensive patrols over the Irish Sea.

In May 1944, it moved back to East Anglia, receiving Mosquito Mk XIXs and supporting bomber streams as part of No.