MacColl's army record was virtually kicked to death on another thread recently (Did MI5 spy on MacColl or something). It didn't reach a satisfactory conclusion then and I very much doubt if it will now.
Next year will see a biography (well researched as far as I can judge) and then we can make up our own minds on whether MacColl was a spy, a deserter or Kaiser Bill's batman with a lot more real information at our disposal.

Jim Carroll