Duxford Investiture 1941 – What was on the Tarmac?

When the King and Queen visited Duxford 16.1.41 for an investiture, what were the American Lend-lease aircraft on the tarmac undergoing acceptance tests with the Air Fighter Development Unit? Were they the Bell Caribou (later called Aircobra) that went into service with 601 Squadron?
The Queen asked for photographs “for the children” – did they they get them?