Sector 7G,
Hi there - I was training the controller who issued that instruction to you on monday morning.
Having discussed the timing of the clearance - the controller is now aware of the implications and alarm it could cause an inbound crew. To prove the lesson was learnt, we were in exactly the same position the following morning to which the phrase was prefixed with 'After the landing.. short final....'
If the retort while you were vacating came across as short - it was not meant to! We were in fact discussing said concerns and in addition still trying to squeeze the departure away before your colleages behind you landed.
I hope this helps, but if you still want to discuss it further contact NATS Heathrow and we would be happy to accommodate you.
CFP.