Through my research available of Rootes wartime vehicle production it states that between 1939 and August 1943 there were just over 6500 Commer Q2's delivered.
I have a Q2 that has a chassis number just after 5700 and is registered as 1942, from the above this would lead me to think that its correct.
I ideally want to find out which service it was delivered too. I am still researching.