While the standard phreaseology is determined in a calm office environment, it is decided based on common sense and experience. And it's changed when it is found to cause problems - for example "Take off" is only used when that clearance is issued (or cancelled), so that this sequence does not happen: PJ123: "PJ123 ready for takeoff" ATCO: "PJ123 Roger" and due to misunderstanding "Roger" to mean that approval has been given, the aircraft takes off. This is two mistakes, but it has happened, so the phrase "Ready for departure" is used nowadays. As for readbacks, again there is a list of what must be read-back, and it includes all clearances, altimeter settings, altitudes, headings and so on. A Go-Around must always be read-back, as it was in this case. If an instruction cannot be complied-with, the word "Unable" is used, possibly with a reason, but just ignoring it because as Captain "you know best" is not just bad airmanship, it is also illegal! Remember that in Controlled airspace ATCO instructions are just that, not suggestions. ("Well Mr.Spock, I like to think of it as the Prime Suggestion" :-) ) And in the UK if you are cleared to land by an ATCO, they are taking the legal responsiblity that landing is safe - how can they possibly do so until the runway is clear of the previous aircraft? Giving "Clear to land number 5" makes no sense as it's fail-dangerous - if a radio failure occurs (or someone doubles, or has a stuck transmitter) the clearance may not be able to be cancelled. On a CAVOK day the pilot can see the runway is clear, but if it's a CAT IIIA Autoland there could be four aircraft piled up on the runway that you can't see! (Obviously a silly example, but not impossible). I was taught that every approach is an approach to a Go-around, and if you can land then it's a bonus - a Go-Around should be a standard, no-drama procedure and not regarded as an surprised mad panic. LHR is incredibly busy - I have watched for a while and timed landings at 40 second intervals, and I think this may be about as close as anyone can do safely. If that means late landing clearances, then so be it - the alternatives are either increased danger or lower runway usage, and neither is going to be acceptable to someone.