Essentially the respectable parties have two options in response to Rochester and Strood.

(1) Say that the Rochester voters have responded to UKIP's policy positions and that to combat them they, the parties, should move in UKIP's policy direction. 

(2) Conclude that they,nthe parties, are failing to refute UKIP's policies and that they need to intensify their efforts to do this. 

Option (1) would be morally indefensible and wouldn't work. The more the Tories or Labour try to pretend they are UKIP Lite the only beneficiary would be UKIP. Why buy a bit more Euroscepticism or a bit tighter immigration controls when you can go the whole hog and get EU Withdrawal and a total ban from the Kippers? 

Option (2) is the only way. Decent people across the political spectrum know that UKIP is a shallow, bigoted, ignorant party with a gut appeal but with policies that could never be implemented and which would be disastrous for Britain if they were. Cameron and Miliband must come out fighting. Not by adopting (a bit) what Farage says (he'd just love that !). But by fighting him on the beaches of the seaside towns (especially) where his fraudulent and shameful message has appeal. And intelligent people of honour should stop flirting with UKIP - and certainly stop defecting to them. Attack them for what they are and start now.