Must admit that Silver Island Site of Special Scientific Interest (SISSSI for short) does have a nice ring to it, as does Silver Island National Park.
Jabird, they lose some marginals they get them back later, it's the nature of marginal constituencies. For every voter upset with aircraft noise there's probably at least 3 who directly or (more likely) indirectly earn a living from the presence and the on-going success of LHR.
Imagine the outcry there would be if Silver (and others) got their way and LHR was closed down.
It's just possible that we are being softened up for a change of policy on this. On the other hand, don't hold your breath!
Forget about a second runway at LGW and HS2 as remedies for LHR's chronic lack of capacity, both are irrelevant. This is a serious problem today, not in the 2020s and will only be solved by an extra runway, or preferably two, at LHR.