@Lasttime - I have been lurking this thread for updates. I, too, knew Allan personally, but it was way back when he still had his house in lowestoft. When I first met him he was an eccentric, amazing, electric person. Absolutely captivating, intelligent, creative. Perhaps he had just hidden his drug use well from me at this point.
But somewhere between about 2008/09 I noticed he went massively downhill with mental health, and I too witnessed him smoking heroin. His behaviour was appalling. He was a different person. he started having young girls over and would give them drugs in hopes of being able to have sex with them. I got in to quite a few vulnerable situations with him and I am so lucky that I got away before I got hurt. I know he had violent tendencies even back then and had been known to slash up furniture in fits of rage etc. He really, really scared me at points.
Before this happened, I had a gut feeling that something might occur with him - overdose, suicide, getting in to trouble. I didn't think it would be murder. It is so tragic, I thought even he was above this.