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 have responsibility for ensuring proper protection of our borders and joined-up liaison between the various bodies responsible for intelligence and security issues. The aftermath of the 7 July bombings demonstrated that, for all the billions of pounds of extra resources that had been thrown at the various agencies responsible for protecting the country from terrorist attack, a breakdown in communication allowed suspects who were briefly under surveillance to fall off the radar, and reappear to commit Britain’s worst post-war atrocity a couple of years later.