Re:RAF Speke (Liverpool, England) USAAF Liaison
Speke was chosen in early 1939 ( ie. pre-war) to receive, assemble and air-test Lend-Lease and Direct Purchase aircraft supplied by the US , initially mainly Hudsons, Harvards and Bostons; the organisation created was the Lockheed Overseas Corporation and they soon began to assemble and test other types for the British. Original personnel were civilian.
Speke became the HQ for the British Re-assembly Division and Lockheed set up other facilities at Langford Lodge ( N. Ireland) and Renfrew (Scotland). In May 1940 the Ministry of Aircraft Production (MAP) took over responsibilities for aircraft procurement from the Air Ministry; about the same time the Lockheed facility at Speke was designated as No.1 Aircraft Assembly Unit (AAU) as Bernie mentioned.
Lockheed , with RAF and WAAFs, were responsible for handling aircraft brought over as deck cargo including de-greasing the components , later crated planes were sent direct to the Base Air Depots.
The Mustangs are from the 55FG (CY), and 22TRS ( QL) and 10TRS ( YC).
Prior to all this several RAF squadrons (including Polish and Czech) were located at Speke.