Actually, I have some sympathy for the idea. Britain is broke and is cutting its military budget as part of a general slash in public spending to cope with the deficit, would it be better to have 4 SSBNs or a cheaper, maybe cruise missile based deterrent and better funding for Britain’s conventional military (especially the Navy, which is woefully understrength in the number of surface ships)?
Ideally, we’d be able to afford the 4 SSBNs we’ve always had, but we aren’t living in ideal circumstances, and compromises have to be made. The whole point about a nuclear deterrent is that it is there to act as a deterrent, not to actually be used. If it had to be used, we’d all be dead anyway.
If we mounted our nukes on cruise missiles, their range and penetratation capability would be more limited, but in the grand scheme of things, I can’t see how it would make the difference between a country deciding to invade or use WMDs on Britain. Even if there was a fairly effective means of shooting the cruise missiles down before they reached their target, you’d have to be mad to run the risk of a nuclear confrontation on the hope that you’d be able to get them all...
"Don't you believe that Great Britain should have the best?"
There is a few problem I see with basing your nuclear deterrent on cruise missiles.
1. A cruise missile has a maximum range of 2,500 kilometers while the Trident has a range of 12,000 kilometers.
2. A cruise missile travels at around 500 miles per hour. This means that it can be shot down be fighter aircraft and anti-aircraft systems.
3. A cruise missile can take several hours to reach its target while the Trident only takes 15-20 minutes.