There are, or were radio receivers available which would, legally, pick up the airband frequencies but were incapable of transmission. I was lent one of these when my mum was visiting so that she could enjoy her favourite hobby of watching the comings and goings at LBA. The sound quality was not wonderful but was good enough to be able to hear which aircraft was approaching (all I needed to keep mum happy) as well as hearing some of the less official transmissions such as "Anyone know who won the golf?" reply -"Sorry, I'm a cricket man myself" Well what did he expect in Yorkshire?! But I digress. Like Heathrow Director I too feel that only properly licensed people should be able to purchase these transmitters. This is one time when public safety should override the civil liberty of being able to purchase anything you fancy.