It seems that Hague is now back wearing his mugger’s baseball cap and taking aim by roughing up his much older Shadow Cabinet colleague in the columns of the press. Will Clarke accept this humiliation? Or, like Geoffrey Howe finally rebelling against Margaret Thatcher’s anti-EU posturing, will he stay true to his pro-European beliefs?

Current Tory hostility to Europe is without precedent in post-war British politics. Even in the worst days of Labour’s Euroscepticism in the 1980s, politicians such as John Smith and Tony Blair were allowed to stand up for Europe. Hague is telling Clarke to renege on a lifetime’spro-Europeanism and instructing all other Tories who want to work with Europe to keep quiet.

In tactical terms, Hague’s appeal may be aimed at trying to get hardline anti-EU voters to return to the Tory fold ahead of June’s European parliamentary elections. But these voters are ready to vote for the UK Independence Party and the British National Party, as those two extreme parties share the same objective of immediate British withdrawal from Europe.

Hague dare not go that far, although the Yorkshire-based “Better Off Out” group of Tory MPs look to him as their man who will so wreck Britain’s relations with Europe that withdrawal becomes possible. However, Hague could not have laid down the challenge to Clarke without Conservative leader David Cameron’s decision to break links with mainstream conservative parties in Europe – the most isolationist move in decades of British politics.

Nominally, the Tories are now looking for partners among European parties who share Hague’s anti-EU fixation. This has already led to an embarrassing meeting with Latvian right-wing politicians who venerate the Waffen SS.

Hague’s hunt for anti-EU right-wing parties with which to align is going to be tricky. One favourite of Conservative Eurosceptics is Philippe de Villiers, the French right-wing MP whose “Movement for France” uses anti-Lisbon Treaty language similar to the Tories. Unfortunately, de Villiers has blamed the current recession on “cosmopolitan financiers” – and “cosmopolitan” in French, as in English, is a codeword for Jewish. So it’s no go there as the Conservatives hunt for anti-EU bedmates.

Phillippe de Villiers campaigning for a 'Non' vote

The other friend of the Tories in Europe, the Czech right-wing Civic Democratic party has just been ousted from power after its leader attacked Barack Obama for taking the American economy on the “road to hell”.

But it is doubtful if Hague is serious about forging links with a ragbag of oddball rightist parties in Europe. His objective is to create conditions in which Britain moves to the exit door of the EU. The implications for global policy and this country’s relationship with the United States, China, Russia and the Commonwealth are enormous, as the Foreign Office faces up to having an openly isolationist Foreign Secretary if the Tories win power.

It should not be forgotten that Cameron won the leadership of his party in 2005 by outflanking David Davis on hostility to Europe. After the first round, there were some 40 Tory MPs who had voted for Liam Fox, who never hides his venomous contempt for the EU which has been a long-standing feature of his right-wing politics.

Fox’s supporters offered their votes to whichever of the two remaining candidates in the race would appease their virulent anti-Europeanism. The price these anti-Europeans wanted for their votes was a pledge to break all links with the European People’s Party – the loose association of centre-right parties in Europe. Pulling out of the EPP was the first step on the road to pulling out of the EU.

To his credit, Davis knew that such a move was unsustainable. He refused to make the promise. Cameron was more cynical and more of an opportunist. He promised to give the anti-Europeans what they wanted. And he then appointed Hague as his chief foreign affairs spokesperson. Hague makes cheap jokes about the French and Germans and has always been an anorak when it comes anti-Europeanism.

In the past, Tory leaders in opposition could play the race card, as Margaret Thatcher did with her notorious “swamped by people of an alien culture” speech. She used this as a “dog-whistle” with which to win back Tory voters who switched to the National Front in the 1970s.

In 1976, Andrew Brons, an extreme right-winger obsessed with the ideology of the Nazi party stood for the NF in a Birmingham by-election and won 22 per cent of the vote. The Tories were worried that the NF would win support from racist admirers of Enoch Powell.

Thatcher’s speech, with its unmistakable xenophobic pledge to stop Britain from being “swamped” (she never said by precisely by whom, but everyone understood who she meant), killed the NF vote and encouraged the Powellite working class to back the Tories in 1979.

David Cameron dithering and dodging European issues

Cameron cannot play the race card. He is a liberal cosmopolitan without a gram of racism in his make-up. To his credit, he has promoted ethnic minority candidates, MPs and peers. He needs votes from Hindi, Muslim and other faith communities in order to win a majority.

Instead, to counter the racist appeal of the BNP, he is playing the anti-European card and using Hague, who does not bother to hide his contempt for Europe, as his dog-whistler.

With most newspapers pumping out anti-EU propaganda and with Labour failing to make the case for Europe with conviction and energy, the Tory strategy may work. But the price of an isolationist Britain will be high. And will Ken Clarke pay it?

Denis MacShane is Labour MP for Rotherham