Having examined the tranparancies it's clearly 2 Devons and the aircraft half hidden by the Valiant's tail is a Shack (the right-hand tail fin is visible).
Two other photos from the same year (1957 - I'm guessing August was the month) with RCyAF Devons and Pioneer.
The Valiant in the last photo looks rather smart, just a routine Far East deployment or could it have been on its way to/from Op Grapple on Christmas Island?
