If Nick Clegg, Vince Cable and the other Lib Dem Cabinet cling-ons possessed an ounce of principle, they would have resigned long before the latest tiff between the coalition partners.

The Deputy Prime Minister can sound as tough as he likes in his criticism of David Cameron's latest anti-immigration bile.

The Business Secretary can appear as oblique as he wishes when placing the Prime Minister in the same lineage as Enoch Powell when it comes to poisoning race relations.

It is as though Clegg and Cable are unaware of a string of previous pronouncements and policies from their own government, targeting immigrants and asylum-seekers and whipping up racist and xenophobic prejudices in a cynical effort to cadge votes.

Then there has been the odious campaign to portray so-called "health tourists" from overseas as responsible for problems in the NHS, which have more to do with underfunding, privatisation and endless top-down reorganisations than with the small number of visitors who fall ill here.

On numerous occasions over the past three years, the Lib Dems could and should have stuck by liberal principles and walked away from a coalition that has turned rancid on questions of asylum and immigration.

That's even before we come the other issues on which the Lib Dems should have abandoned the Tories and left them hanging in breeze.

How did the party of David Lloyd George and William Beveridge end up supporting the ongoing pogrom against unemployed, sick and disabled benefit claimants?

Why has the party of Jo Grimond and Jeremy Thorpe been complicit in the closure of dozens of Remploy factories, dumping several thousand disabled workers on the scrap heap while claiming that they would all find "mainstream" employment?

What was the party of Charles Kennedy doing in the lobbies last August clamouring for British military action against Syria?

Where is the party of John Maynard Keynes that would have savaged an economic strategy which prolonged the recession, stunts recovery and condemns more than a million young people to unemployment?

Come to that, where is the party of Nick Clegg which pledged not to increase student tuition fees and presented itself in Labour-voting constituencies in 2010 as the "real opposition" to the Tories?

That Liberal Party is deader than Monty Python's parrot. What exists today is a shoddy shower of parliamentary careerists who retain only one position from their more illustrious predecessors.

That is their undying, overriding and obsequious commitment to the European Union.

Only this can explain Lib Dem opposition to the Prime Minister's proposal for a cap on immigration from Bulgaria and Romania when their citizens achieve full rights to visa-free travel from January 1.

The Lib Dems believe that the future of British monopoly capitalism - and of value-free minority politicians such as themselves - lies more with the undemocratic and superficially class-collaborationist European Union than with the United States.

At the same time they accept the subservience of Britain's military and intelligence services to US imperialism, ever seeking to ride two horses at once.

Only this distinctive position provides the Lib Dems with any rationale for existence.

For real liberals, socialists and progressives on the other hand, opposition to immigrant-hating and bating must remain a matter of sincere principle.

Everyone coming to Britain in search of work and a better life should be welcomed as fellow human beings and treated with dignity and respect.

It is capitalism - now enforced by EU treaties and institutions - which fails to provide a decent quality of life in the country and local communities where most people would otherwise prefer to remain.