I’m going to have to search through the archive (although I know I’m thin on Whitley items).
The Whitley’s yoke was similar in design to that fitted to the Wellington and the Stirling, an ‘H’ section U shaped yoke with the release at the base of the U.
Try looking for the Arms and Armour Press reprint of the RAF Airborne Forces Manual (ISBN 0-85368-163-5) which has a diagram of the Whitley’s yoke on page 253.
Has anyone got photos of Spitfires towing Hotspurs? I have copies of the reports for the Mk V and Mk IX, and I know that Farnborough tested the MkI. All I have is a photo of the tow hook on the tailwheel.