Sorry but there actually must be plenty of spare R/T time as some genius has come up with the idea of approach controllers specifying the stack in which an a/c is holding when sending instructions, eg "In Biggin, Speedbird 999 descend FL80". It's supposed to prevent near-stack incidents, although how it's supposed to work I don't fully understand. If it works the scheme will probably be adopted nationwide... then expect London Control to say things like "Seventeen and three-quarter miles bearing zero seven seven degrees from Houghton Regis, Speedbird seven seven seven descend FL 110". Seems perfectly OK to me... Only minor problem is that aircraft will have to carry either the AA Book of Air Navigation or the complete series of OS Landranger maps so they can determine if it's them being called by working out their exact location...