Here are a few thoughts from a controller in the LTMA.
The 270 kts is a very poorly thought out idea, causes many problems and solves none. I agree with the comment that it is from an office worker 'trying to make a name for themselves' It should be scrapped immediately and let the pilots and controllers get on with their jobs.
If the landing rate is 38 and 42 are flowed in to LL, then there will always be holding. If you want to reduce holding, reduce the numbers of aircraft flowed into LL to match the achieved landing rate.
The choice of which aircraft to stack swop is complex. The person taking the decision will normally be one of the Group Supervisors (GS) in TC. The CLN sector should be prepared for the aircraft to be at FL150 level by SABER. Height is normally more important than speed.
The GS will be looking at the overall picture of inbounds to LL eg, is the cruising level OK to hold at BRASO? or how does this aircraft fit in with the inbounds to BIG from the SE? or which is the easiest for TC. Often the aircraft chosen will be the one(s) to the south of a bunch.
The problem on Saturday was more to do with flow. It was very quiet all afternoon and then a large bunch of planes arrived together. If flow was more precise, then perhaps these planes would be more spread out. Would it be better to issue an arrival time at BRASO/LAM rather than a slot departure time that can be 20 minutes wide?