On behalf of Sarah Green:

 

Both C and D are liable in Conversion. This is reasonably similar to both Indian Herbs (UK) Ltd v Hadley Ottoway Ltd and ors [1999] EWCA Civ 627 and Jarvis v Williams [1955] 1 WLR 71 (CA), although in the latter case there was no liability since the necessary right to possession was lacking. On the facts you have given, the immediate right to possession would revest in A on abandonment, whether or not A knew.

There would be no ius tertii if the terms of the agreement between A and B dictated that B's possession was to cease on abandonment/cessation of payment.