Of the unaccountable absences in the current General Election campaign, the void around the Deputy Prime Minister is perhaps the deepest and least puzzling. The irony of a contest dominated by pluralism without a Liberal element is fast becoming axiomatic, and the lack of any serious constitutional debate in the situation where it is clear that the electoral system will deliver perverse outcomes demonstrates Clegg's failure to capitalise on his time in government.
About the only demonstration that Britain has had five years of atypical government has been the needling by the right-wing press surrounding the post-election relationship between Miliband and Sturgeon. They are being astute in not committing, with the SNP prodding and Labour resisting, to a full-blown arrangement similar to that with which Cameron ensnared the Liberal Democrats in 2010. A minority administration is a perfectly legitimate outcome - for example building on Labour's experience after 1929 and the Liberal administration after the triumph of the Irish Nationalists in 1910. In a country obsessed with historical precedent, this is hardly revolutionary.
Clegg has undermined the credibility of coalition by his eager-puppy embrace of the Tories. However much there is a justification of naivety, the reality of the situation that he found himself in was that there were very few stable choices open to him, especially after Labour had made it clear that they neither had the appetite nor the discipline to deliver a stable arrangement. This should not be forgotten, as it is one point in his favour. Yet the idea that the Coalition was an end in itself, not two parties collaborating for the necessary pursuit of government, has fatally wounded Clegg, and while he remains leader, the Liberal Democrats.
While the Liberal Democrat manifesto is a mature piece of work, informed by some residual radicalism that has not been completely demoralised by five years of stoogery, it will probably end up as irrelevant as the party has no clear identity. If it manages to persuade a few more of us to vote tactically then that will be some achievement - because after five years the various vote match sites produce for me, and I suspect others, wildly varying results depending upon which nation you start your journey from.
It is difficult to articulate what the Liberal Democrats stand for at this election - there's no enthusiasm for anything beyond survival; keeping the flame of constitutional reform and federalism alive should have at least been a point of differentiation. Now the pace is being made by the Scottish and the Welsh, with the consequent petty xenophobia and English particularism that plays well to Cameron's desire to court the Kipper dribblers. For a party with a tradition of questioning the establishment, to have been subsumed, played with and spat out, this should be seen as humiliating beyond belief.
Clegg's final piece of foolishness has been to position himself as midway between a profligate Labour party and the austerity-mad Tories. While the latter remains the hidden agenda of the Bullingdon drones, the way in which this campaign has turned has reversed the analysis - Labour are the party playing up responsibility, while the Tories are running around looking for client groups to shore up with unfunded promises. A mistake that placing a party in the middle of two others always leads to, and one which should have been learned.
From an insurgency to an irrelevancy in a decade - hardly a legacy that Clegg will want to reflect on if he is rejected both by the electorate and his own party. An unprincipled centrism leads to defeat - and the natural radical scepticism, rightly or wrongly, is moving to the Greens, Plaid and the SNP, with the inchoate, unwanted ranters, continuing to drift about. Clegg's short-term stupidity and the arrogance never to admit to having got anything wrong, preferring the rhetoric of "tough decisions", may cost the genuine radical liberals and mavericks dear. They may be waiting for a very long time either for a recovery or an apology from a failed leader for a failed approach.