We already have the NHS, do we need a DHS too?

Earlier this year Con Coughlin argued in The Spectator:

Clearly there is a need for the government to get a firm grip on all the various security challenges that might come our way, which is why there has been much talk at the Cabinet Office, which is overseeing the review, of establishing a National Security Council along the lines of the body in Washington that advises the White House on security policy — both short-term and long-term… A better alternative might be to set up our own Homeland Security Department — represented by a minister of Cabinet rank — which would...