In recent times, on being told of Leighton Andrews' defection to Labour I've consistently dismissed it as being for too improbable. Indeed, to have done otherwise would have been akin to emulating Lewis Carroll's White Queen who "sometimes believed as many as six impossible things before breakfast." Leighton Andrews? The colleague who kept the rest of us in line. The solid, dependable comrade whose Liberal instincts and libertarian heart could always be trusted. The anorak wholly at ease with fellow Liberator revue satirists. The writer and editor whose solid work provided vital reference points. The intellectual Liberal prepared to take on David Owen and all comers at radical conferences. The friend as responsible as any for the tactics which got me elected in 1983. Impossible!

But, astoundingly it is true: Leighton Andrews is the Labour candidate for Rhondda in this year's Welsh Assembly election. It is far too easy to dismiss defections from one's party as being of no importance, just as defections to one's party are grossly oversold as being of planetary significance. Leighton's switch of parties is different. It is not evidence of earlier being in the wrong party for his beliefs and personality, as was, arguably, Peter Hain. All of Leighton's pre-1996 speeches, writing and campaigning are consistently and solidly Liberal. New Labour is instinctively conservative and increasingly illiberal; one only has to read Nick Cohen's articles in the columns of the "Observer" and the "New Statesman" to see the evidence set out vividly. With a track record like Leighton's, to become an advocate at this moment in politics for what is a travesty of even Labour's heritage and of any moral stance requires a massive disavowal of his previous principles and views. Perhaps unsurprisingly, all Leighton's current short biographical notes fails to mention anything of his Liberal past.

It was Leighton who coined the acronym LINk - "Liberal Information Network"- for the radical Liberal ginger group formed after the 1983 election, and who was the motivator of the group and of its radical conferences. Between then and 1987 he produced a series of excellent publications and articles. His booklet, "A Good Age - a Liberal Approach to the Politics of Ageing", is both a powerful analysis of the stereotypes and a trenchant critique of the Conservative and Labour approaches.

"Labourism's approach," he writes, "which depends on a centralised strategy, the achievement of certain, probably unsustainable levels of economic growth, and an emphasis on the scale of resources rather than the assessment of need and allocation of resources according to need, seems dedicated merely to perpetuating existing structures and confirming existing deficiencies.

Labour is also suspicious of voluntary effort .... No self-criticism, no awareness that the state is not necessarily benevolent or even neutral, no commitment to pluralism."

Interestingly, there is now a Labour commitment to pluralism, but of the market rather than of the voluntary sector - a Conservative attitude equally derided in the same booklet in which Leighton set out "the Liberal Alternative: independence, choice, power".

In the following year, 1985, Leighton produced the pamphlet "Liberalism versus the social market economy". This was a lucid and trenchant critique of David Owen's economic policies and of economic determinism, and a restatement of Liberal principles on the integrity of the community and on the vital need for economic and social welfare policies that promoted unity not division in society. In clear contrast to new Labour's shift towards Owenite views, Leighton wrote:

".... there are fundamental reasons for arguing against a transfer to means-tested welfare benefits for political activists seeking to challenge the divisions between those in and out of the workforce. Means-testing generally involves stigma, low take-up and a sharp division between those seen to be 'enjoying' the benefits and those paying for them. For a political party seeking to create a sense of community, as well as flexibility in employment patterns during the life-cycle, the Liberal universal tax credit scheme is the only way forward."

In the autumn of 1984 Leighton became a member of the "Liberty 2000" group which was set up the "reassess Liberal themes in the light of the need to reverse the intellectual dominance of Thatcherism." He was also the Vice Chair of the party's Standing Committee (on policy) and a member of the party's National Executive. He wrote the initial booklet, "Liberalism after Thatcher", and was the author of the group's final report, "Liberty in Britain". Again, as one would expect, Leighton produces a rigorous analysis of Thatcherism, often juxtaposed with contemporary Liberal writings, but, in his conclusion to "Liberalism after Thatcher" he also criticises Labour's flawed approach:

"..... despite the efforts of some decentralist socialists, Labour's response to the problems of the state has been little other than more of the same. ..... Labour seeks to defend the indefensible by promising unrealistic public investment based on incredible gowth levels. Real problems, many given to us by Labour governments and by municipal Labourism, are left unattended. Too many vested interests exist for it to be otherwise, particularly in the unions which, being centralised organisations, largely need centralised economic structures within which to work. The legacy of Labour's post-war involvement in the planning of the welfare state also lingers on, particularly with their peculiar hostility to voluntarism."

That sounds about right - and entirely consistent with all Leighton's writings thus far, and with his valiant efforts as the Liberal Alliance candidate in Gillingham at the 1987 General Election. However, at around this point, possibly following the relatively disappointing result at Gillingham and the Steel bargain basement sell off of the Liberal party, Leighton understandably concentrated on his professional career, eventually becoming, in 1993, Head of Public Affairs at the BBC.

By 1996 he was contributing an untypically dry chapter - "New Labour, New England" - to a largely left-wing collection of essays, "The Blair Agenda". This has all the marks of an Andrews essay: erudition, skilful handling of material, well structured, but with a complete lack of apparent commitment to any "line". It is in effect an academic position paper rather than a political argument. And in any case, why spin out twenty pages on Englishness, as opposed to Welshness and Scottishness, without grappling with the whole illogicality of the concept of sovereignty, or the more immediate realities of certain "natural" identities, including, for instance, Yorkshire or Cornwall? Of course the arrogant belief that "British is English" by so many south of the border is important and intolerable, but Leighton's final conclusion is hardly a clarion call for anything:

"Tony Blair's conception of new Britain fundamentally challenges the conclusions of decades of cultural thinking on the left of British politics. Alternatively romantic and pessimistic in turns, that cultural theorising has blocked the evolution, until recently, of a positive and dynamic Englishness conceived independently of the institutions of the British state. In a context of radical constitutional change, a psotivie sense of Englishness may be one element needed within the culture of Labour and the left to entrench that change and enable Blair's 'new Britain' not only to develop, but to survive."

Come off it! This is sheer pastiche, and if I or any of Leighton's friends had written it we would have rightly suffered a typically withering putdown. In retrospect, however, it shows the telltale beginnings of a shift of allegiance.

Coincidentally with this publication Leighton was appointed to a Welsh quango by William Hague but then metamorphosed into a key role in the "yes" vote campaign in the referendum for a Welsh Assembly. Recently Leighton wrote to me saying that "Welsh perspectives are different from English ones" and so they are, but when they lead to supporting the Blair nominee, Alun Michael, for leadership of the Labour party in Wales in a deeply flawed election system, the perspectives are alarmingly different. Paul Flynn's Welsh perspective on Leighton is vitriolic. In his book on the leadership campaign, "Dragons led by Poodles" he calls Leighton, among other things, "oleaginous, accommodating, feline, apprentice shape-shifter". This description bears no relation to the colleague we worked with so enjoyably for many years. What has happened to the Leighton we know and love?

In recent days Leighton, as one would expect, has been putting out a stream of comments on current events as they affect his constituency. All are boringly supportive of the new Labour line. For instance, he suggests that there are "four principal interlocking areas of policy that are essential in dealing with the drugs issue." Leighton's quartet of policies do not include any hint that decriminalisation has a key role. His main opponent accuses him of defending Blair's support for America against Iraq.

How the mighty have fallen. To be in the wrong party at the wrong time, backing the wrong horse within that party, when, particularly in Wales, it is not needed to achieve political advancement, is particularly perverse. What does this say about this former colleague? What does it say about the Liberal Democrats? And, indeed, where next for Leighton?

February 2003