You'll never get an answer to that on here Danny. My guess is we would not be able to respond with 12 jets/pilots for very long, or if at all and the situation would deteriorate for the UK (if it came to any sort of rolling operation).
Plainly the Russian Air Force will be under instructions to keep at this with an ever increasing slowish rise in tempo as we approach our General Election and (b) as long as it suits Putin to neutralise PM Cameron's role in any way of influencing the outcome of the on-going hybrid war in eastern Ukraine.
It would suit Putin to embarrass Cameron, something militarily he is easily capable of doing.
I expect the Russians to push into UK airspace soon. And it will come down to the young guys and women in the cockpit and older wiser RAF heads on the ground to de-escalate the situation.