While Tom and Luke are right that without winning elections you can't do anything, there is a truth in what Neal Lawson says, politics should be about having a belief and gathering support around it. 'At the other extreme' politics just ends up being a cowardly affair where you blindly follow whatever the consensus is (a consensus unfortunately affected by the 75% of the press that is Tory). Labour has given up trying to lead opinion in the face of this ferocious opposition and not only disenchanted it's core support but now faces losing elections (the only justification it had for moving rightwards in the first place).
Once again and I bet you saw this coming, our present electoral system encourages politicians to just follow consensus rather than really campaign for what they believe in.
Under this electoral system Labour are caught between moving rightwards and totally alienating masses of core support in safe seats or inching left and losing the few middle class 'voters that matter' in the marginals. The bias is always to move rightwards - which is exactly what Labour has done and have lost 4 million plus votes in the process but heh they still kept enough to win elections so what does it matter? (well it will matter when the Tories enlarge the boundaries).
Why does this not equally affect the Tories to move to the left? Well the Left historically are more split, lefties are more independently minded (this also partly explains why atheists are weak lobbyists in comparision to the religious). Our electoral system is ruthless to beliefs that are split beween parties, the plethora of socialist parties, Greens, Lib Dems, SNP, PC etc eat up votes that combined could win seats for the left under FPTP. The Tories in comparison are not so split and can end up winning big when they do not have the majority support to deserve to win.
So if we want Neal Lawson's ideals of what the Labour party could be doing and also see Labour winning elections, then we need proportional voting. Of course this is not a moral argument for PR, but luckily morals are also on our side because our democracy is just 'one person one vote' when it should be 'one person one equal vote. I've said it before and I will no doubt say it again but where you live should not be more important than how you vote.