As I recall, the UK MLS trials work was split between Farnborough, who had responsibility for the technical signals aspects, and Bedford who looked at the operational (RNAV) aspects using a BAC 1-11 and HS 748.
IIRC the theoretical studies for MLS advantage over ILS at LHR (and MAN) considered reduced approach spacing due to lack of interference / co channel problems, and multiple approach path sequencing (environment).
Intermixing steep approaches (with different/inset thresholds - low noise) was considered for normal / STOL capable aircraft, so too for helicopters, which additionally could use variable / offset approach paths and angles without disturbing conventional traffic.
There were also advantages (mainly environmental) for missed approaches and departure routing.
All approaches were designed for Cat 3.
There were several MLS ground units; a semi permanent facility at Bedford with temporary installations at LGW, MAN, Berne, and Tehran in support of the British bid for the ICAO MLS standard.