I've been trying to help. And I'll try this one LAST time. You ask what happens in the UK in practice.
Controllers will follow the national procedures in the Manual of Air Traffic Services Part 1 (and any local modifications - which are not normally in the public domain). This document currently says:
When aircraft are using the same runway, a landing aircraft may be permitted to touch down before a preceding landing aircraft which has landed is clear of the runway provided that:
a) the runway is long enough to allow safe separation between the two aircraft and there is no evidence to indicate that braking may be adversely affected;
b) it is during daylight hours;
c) the preceding landing aircraft is not required to backtrack in order to vacate the runway;
d) the controller is satisfied that the landing aircraft will be able to see the preceding aircraft which has landed, clearly and continuously, until it has vacated the runway; and
e) the pilot of the following aircraft is warned. Responsibility for ensuring adequate separation rests with the pilot of the following aircraft.
The phraseology used to authorise a landing aircraft to touch down before a preceding landing aircraft is clear of the runway is "LAND AFTER the (aircraft type)".
Yes, it is not consistent with the current ICAO PANS. The current UK procedures do not appear to implement ICAO reduced runway separation criteria.