I had (selectively) forgotten about my solo XC... trying desperately to get hold of Wellesbourne:
"Wellesboune Information, Helicopter X-XXXX"
<no reply> <repeat> <no reply> <repeat>
"Helicopter X-XXXX: This is East Mids tower, please check your frequency."
"Errr, my apologies sir. Helicopter G-XX."
Sure enough.... one turn too far on the dial!