Did his 'friends' actually exist...

...or where they merely projections of his deluded psyche - were Colin, his wife, and the waiter the only real characters?
It seemed to me that all the thugs could have been representations of facets of his own personality and that he could have kidnapped the waiter on his own - he even leaves the building unaccompanied at the end. All the other players are happy to let him call the shots and and effectively only actually offer up advice, we see no other real involvement from them that can't be attributed to Colin's pursuit for revenge. Even McShane's character's homosexuality seems to surface in Winstone's dialog when he is talking to Loverboy. Yes, there was the occasional side thread (the £40,000 win) but nothing concrete.
It's only a thought, but it did get me thinking that it might not have been as straightforward as it appeared