Colin suspected he would try and sell them this is why he tried to get them back but it was too late.
Hi Susan, does Colin say this in his book?
According to his witness statement, Jeremy informed Colin of the existence of the photos and agreed that Colin could have them in order to destroy them. This was after Jeremy had cleaned up Sheila's flat. There is no suggestion that Colin suspected that Jeremy would sell them and the discussion was clearly amicable. In fact it seems clear that Colin suspected that the relatives were trying to frame Jeremy.
In fact Colin was so unconcerned about Jeremy's holding of the pictures that he went to stay with friends in Cornwall for a week leaving only a loose arrangement with Jeremy to collect them at a later unarranged date. These do not appear to be the actions of a man who suspected that Jeremy would attempt to sell them.