Ah well, we've already discussed the problems of BA arriving early ....
Also, it's Dean Cross, not Dean's Cross.
If you can't read back a clearance on the first prompt, that will presumably mean that you are going to have problems with complying with it, doesn't it?
The most important one is conditional line up clearances. That's partly what killed so many people in Tenerife - and more recently a pilot in Paris. People have to know what is going on - and know that you know what is going on as well. This is not a question of following rules, but airmanship. Following rules might not be enough to save your life.