Perhaps a more appropriate question might be:-
If the RAF continues to close bases, then at what point would a single weapon destroy in a millisecond our country's entire offensive and defensive airpower. An advantage of positioning one's forces near to each other is the availability of support and centralisation/rapid comms, a downside is that your eggs are in one basket - eg Egyptian airforce 1967 (how far back do we need to go for an object lesson?) or Hawaii 1941.... or even more an example, Phillipines AFTER the war warnings went out post Pearl Harbour.
The closer together we base an ever dwindling number of assets, the closer we come to becoming a good bet when bad folks consider a pre-emptive strike. We aren't 'only' dicking with defence now, we are entering the arena of being plain foolhardy. Thank goodness we get on so well with the French these days...
Dave