I'm not sure where 'TM0486' comes from in this instance, but I note that it is used several times on the net. The Sqn ORB states this a/c as Lancaster III serial JA915 (coded 'GT-U'). There is a loss report at The National Archives at Kew under file ref AVIA 5/22/W1646. Unfortunately these are not digitised, so you will have to get someone to make a personal visit.
As you are probably aware, photos of 156 Sqn are notoriously hard to come by.