Why cite FAA standards?
UK CAA allows for wake turbulence separation minima to be applied between pairs of aircraft until 4 dme, provided the following aircraft is at same speed (or slower) than lead aircraft when the first passes 4 dme. Not to touchdown.
UK CAA continues to build on a huge database on wake turbulence encounters by encouraging a very healthy reporting system whereby both flight crews and ATC are requested to report on any incident.
This isn't anything new for the UK. Wake turbulence separation to 4 dme (not threshold) has been in place for decades. In my experience, the worst upsets inbound to heathrow have occurred in the initial and intermediate approach rather than final.