It is hard to exaggerate the scale of the immigration crisis that now faces Tony Blair

After the 2001 general election massacre, a consensus swiftly established itself in the Conservative party. William Hague had fought on the wrong issues. Instead of Europe and asylum, his chosen battlegrounds, he should have championed health and education. Hague’s mistake, so conventional wisdom held, doomed the Conservatives to be the rancid voice of the malcontents, the losers, the racists: the detritus of 21st-century Britain.

This persuasive analysis, associated above all with the so-called ‘modernisers’, swiftly took hold in Tory high command after Hague’s abrupt departure. It held sway under Iain Duncan Smith, and even more so under Michael Howard. For the last three years prodigious efforts have gone into establishing the Conservative party as sound on public services. This project reached its culmination back in February, when the shadow Chancellor Oliver Letwin promised to meet Gordon Brown’s hugely ambitious spending targets for health and education.

This was the moment, so the modernisers felt, when the Conservative party returned to the British political mainstream. Europe seemed to have gone off the radar screen, asylum-seekers reduced to a bureaucratic argument, the Hague heresy expunged. The Conservatives seemed set to fight the general election, most likely to be held on 5 May next year, on public-service reform.

But elections can never be worked out as abstractions. They are always forged in the white heat of events, and events have moved precipitately in the last two to three weeks. First came the al-Qa’eda bombs in Madrid. These brought about instant regime change in Spain, with the consequent loss of Tony Blair’s closest European ally. As a direct result, the European constitution —- blocked by the Blair/Aznar alliance — is back at the top of the agenda.

This is a very difficult issue for the government.