Back in 2010 the AOG team of which I was a member ran into this question, and couldn't get a definitive answer from the CAA. Eventually, to avoid any further confusion, the company decided to pay for us all to go to the local airfield (Ours was in Newtonards, near Belfast) and do the CAA Flight radio Telephony Licence training and exam. Can't remember how much it cost, it wasn't a lot, but it's valid for ten years.