When this photo was sent to me the caption read: "The RAC motorcycle racing team in Llandrindod Wells, Wales, UK, for the International Six Day Trial in 1938".
The motorcycles are Internationals and by the height of the camshaft tunnels could be 348cc M40's. With the exception of the knobbly tires the Nortons should be more suitable for fast road racing! The bike on the right has a wrap-around racing oil tank fitted.