Swap Trident for the Carriers...
Lewis - I agree with you most of the time, but I think you're wrong here...
The main problem with scrapping Trident is it makes it harder to argue we should put Nuclear into the Carriers. As far as deterrence goes Trident is pure vanity.
The only nations with nukes & delivery systems that Trident could deter are US/France/Russia and China. We can hope that 2 of those are on our side (ha!) and the other 2 both have enough warheads they can blow us up, take a full-scale Trident strike and then blow us up again.
We should cancel Trident and Eurofighter T3. Put some of the money into Nuclear carriers (we still have nuclear attack subs, so we'll keep the infrastructure) with catapults. Scrap the F35-B and get -Cs for the Navy. The Riff-Raff can get F35-As with the money we'll save from T3 and we'll still come out ahead.
Taking the defence argument further, the Trident savings will have enough left over to build some more helicopter/marine carriers to help with peace-keeping/anti-piracy jobs.
We can reduce the threat from dirty/terrorist nukes by growing testicles and adopting a non-US-centric foreign policy (the Lib Dems would help here I think).
On nuclear power; you're right, we can't do without it, but we *do* need to work out what to do with spent fuel for the next 50K years - I'm not sure that ponds at Sellafield are a good long-term solution - so the quicker we get Fusion going and move away from Fission the better.
In truth, this argument is largely redundant as even the most woolly liberal knows they won't be in power by themselves on Friday. I do hope that they can get Trident brought into the defence review (and so save the Carriers, which look likely to get the chop otherwise), but no-one really thinks anyone (even a Liberal PM) would actually bin civilian nuclear and that certainly won't happen in coalition.