It's interesting reading this. Have never read Colin's book and always had the impression that Jeremy and Colin had been quite close, am sure I have read before they were 'like brother's'. Obviously, this was not the case and it seems they were more like acquaintances than friends, it puts a different slant on things imo.
People seem to think that they were close because Jeremy complained about his family to Colin. He complained to Colin because he knew Colin didn't like them either and thus he was a god person to tell. In any event he complained about his family to a wide variety of people he wasn't shy to trash them. His co-workers telling police about such trashing didn't do him any favors his big mouth extended to more than just being too open with Sheila.
After the murders he wanted Colin to believe Sheila did it so naturally interacted with him and tried to convince him by feeding him lies such as the claim the family was going to force her to give the kids up - which he laughed at because they forgot they would need to secure his permission but it was made up they actually simply talked about part time help for her. Jeremy knew part time help would not convince Colin that Sheila had a motive so he exaggerated. Apparently he figured since police didn't know Sheila he could tell them the truth about it just being part time help AND/OR he knew others would tell police it was just part time help they were planning and he figured he had better not lie because it would look suspicious.
The same people seem to think he was really close to Brett Collins as well. I seem to have a different idea of close than most people. I suspect Collins didn't rush back to the UK upon learning of the murders to support Jeremy because he wanted to console his friend. I suspect he rushed because he figured Jeremy was loaded now and figured they could party hardy. It is like when people hear their friend got a huge insurance settlement then when they are broke again the rats flee the ship. Party friends are not true friends. Jeremy might not have had any true friends for all we know. True friendship is a two way street, who was Jeremy a great friend to? Many people have a lot of superficial relationships and few real ones. Clearly we don't know everything and I could be wrong, Brett and Jeremy could have been gay lovers who got close emotionally for all we know but I think that is unlikely. I think Jeremy and Brett were both using eachother.