Bags,
Did and reckon my comments are still valid -
If the SLF don't want to use it, then you can't force them to.
Closing them down to open up airspace seems an odd proposition when there are other options that would free up airspace and (existing) airfield capacity - doing away with alternation at LHR and allowing flex departure tracks would solve the short term capacity constraints.
The political quotient will always get in the way though because the Westminster Crew seek election/re-election but if the UK is to prosper, it needs strong political leadership with the long-term vision to lay out the roadmap to growth.