Could someone please explain briefly what MLS is please?
Unfortunately, as it has turned out, a complete waste of money!
The only real advantage is that, due to the greater tolerance to interference of the microwave signal, reduced spacing can be achieved during low vis ops but unless you have either:
all aircraft equipped with MLS; or
a dedicated MLS-only runway
the benefits are not really tangible.
At LHR, a stream of BA Airbii may save a few seconds but the following ILS-only aircraft will still need standard spacing.
GLS (GPS Landing System) offers similar benefits but again, few airports and aircraft are so equipped.