411A ,
your reply seems to suggest that the UK way of handling Air traffic ,being so pedantic as to say "CLEAR" to land is unexpeditious,and yet the busiest airspace in Europe is still dealt with.
Admittedley we are not moving the same traffic as in the states but we do it on single (or in HTW,s case) dual runways. We do not have the physical space to operate on 9 or 10 runways or to speed control aircraft from up to 200 miles out.
The most important point though,I feel ,is that when I give a pilot an instruction, they know it to be Absolute.
The runway is clear,the go around track is clear, the overhead is clear and therefore you are cleared to land.
If you want to tell aircraft they can land when they are number three,use another phrase ,but do not tell them they are CLEAR