Thanks for the clarification Chevron , I remember the pre SID rather tedious readout which I imagine just got too much for the LHR traffic load. If I recall right early on in the SID era didnt get IFR clearance at startup but as they approached the runway they had to back to LHR Clearance on 121.7 for airways clearance which probably wasnt ideal given that i presume flight deck work load approaching the runway or holding point is pretty high. I also rather liked the idea of the Something airways XXis cleared to some exotic place or other and even thats gone as its all done by data link. Another little bit of the magic of flying gone.
As an aside during my years living in Bermuda I took mum in law to the airport for the only night civil op the BA 2232 to London , LHR at the time I am referring to.
Bermuda Airport (Kindley Field as it was colloquially known) was an active US Navy airstation . The US Navy controllers filed the flight plans and gave startup clearances and then handed back to the ramp controllers, civilians, for push and taxi. . Once again airways a clearance was given just prior to take off .I was listening on my little airband as a US Navy controller cleared the BA 2232 to London via , a couple of rather fishy named waypoints, then all the Atlantic crossing waypoints and finally, Lands End , Southampton Midhurst ... at which point a very 'old fashioned' BA voice cut in with a 'Thank you, I think we can find our way from there'.
i dont think LHR would have coped with having to give everyone that treatment , but for those of us 'on the outside' much of the interest in listening to Airband once one had figured out the generality of what was going on was to hear these occasional wholly human remarks , some exasperated some amusing.