Timmyhawk

As explained below we cannot reverse nuclear arms already aquired in the countries that have them. So, a realistic policy should firstly work at reducing their numbers, an area in which Britain is leading by example. The next realistic step is to stop further proliferation. The risk of this exists in two broad regions: the Pacific and the broader Mediterranean and greater Middle East.
Let's get the Pacific out of the way, as this is outside Britain's strategic sphere. The consequences of North Korea getting away with its programme and a possible weakening of American leadership could lead to the following chain reaction of nuclear weapons aquirement: South Korea & Japan, Taiwan, Australia and Indonesia.

Looking into our own region, let's have a look at the consequences of a nuclear-armed Iran, coupled with a possible drawdown of US-UK regional military policies: Iraq, Saudi Arabia and Turkey as the first in line would go nuclear first. In turn this would pressure and open opportunities for Egypt, Lybia and Greece. Leading on from there Algeria and Syria can also not be discounted entirely. Once this is getting underway, who can say that other European powers, especially Germany will not be tempted as well? Additionally remember the strategic pressure represented by Russia.
This is bad for Britain's security. So, in order to counter this we will have to work on strategic arrangements and security deals that will lift the potential burden of Iranian/Russian nuclear blackmail from these countries. This would require resetting our alliances and making it clear that armed conflict will at some point draw in British military force, which must, and will, ultimately be insured with nuclear weapons.
Such a policy would not be able to reverse nuclear weapons in any of the countries in our strategic neighbourhood (Britain, France, Israel, US, Russia, Iran), but it would prevent the spread of such weapons to other countries.

(See also this article in the JPost by Emanuel Adler on the Israeli case, which makes a good point, similar to mine, and which ties in with this earlier posting).