How kind of Keith Vaz MP (Lab, Leicester East), the shy, retiring chairman of the home affairs select committee, to turn out at Luton Airport yesterday to greet the first flight from Romania since entry restrictions were lifted. One of his colleagues on that committee, Mark Reckless (Con, Rochester and Strood), went along too.

Victor Spiresau turned out to be the only Romanian on the flight who was arriving in this country for the first time. He told Mr Vaz: “I don’t come to rob your country. I come to work and then go home.” Nor was the plane on which he arrived full. So it seems that some of the reports of Romanians and Bulgarians falling over each other in their haste to reach the United Kingdom were exaggerated.

Certainly the warning by Nigel Farage, the leader of UKIP, that 29 million Romanians and Bulgarians now have “untrammelled access to Britain and our labour market” is not a very helpful guide to how many will actually decide to come here. Some at least of those people will decide to remain in Romania and Bulgaria, and it appears that quite a large proportion of those who want to come to Britain have already done so. But the only honest answer to the question of how many migrants will arrive here is that we do not know.

And there is a second, even more important, question to which we do not know the answer. How many of the migrants who decide to settle here will very soon – I mean at latest in the second generation – become British?

It is entirely legitimate to warn of the dangers of mass immigration. A high rate of immigration is likely to depress wages for people in the same trades as the immigrants. If housing is in short supply, the arrival of more people is likely in the short term to make the problem worse.

But many who have warned of the dangers of immigration have underestimated the speed with which the new arrivals would become British. Enoch Powell seems to have assumed that most immigrants would continue to lead separate lives in separate communities. In his “Rivers of Blood” speech on 20 April 1968, he said:

“We must be mad, literally mad, as a nation to be permitting the annual inflow of some 50,000 dependants, who are for the most part the material of the future growth of the immigrant-descended population. It is like watching a nation busily engaged in heaping up its own funeral pyre.”

Powell was a great man, and as he said at the start of that speech: “The supreme function of statesmanship is to provide against preventable evils.” His warnings against the dangers of joining what was then the European Economic Community remain as resonant as when he first uttered them. As he said in Lyons, in France, on 12 February 1971:

“Take Parliament out of the history of England and that history itself becomes meaningless. Whole lifetimes of study cannot exhaust the reasons why this fact has come to be; but fact it is, so that the British nation could not imagine itself except with and through its parliament. Consequently the sovereignty of our parliament is something other for us from what your assemblies are for you…your assemblies, unlike the British parliament, are the creation of deliberate political acts, and mostly of recent political acts. The notion that a new sovereign body can be created is therefore as familiar to you as it is repugnant, not to say unimaginable, to us.”

But what has happened to this Parliament to which, quite rightly, Powell was so devoted? It contains an increasing number of members who are of recent immigrant origin. And we can be certain that Powell would regard those members as the equal of any other members.

For this is one of the ways in which immigrants and their descendants demonstrate that they have become British: they start to take part in British politics. Britishness turns out to be a much more elastic concept than Powell, with his brilliant but rather rigid mind, was ready to see.

Many immigrants come here because they want to be British. They admire our tradition of liberty, and also our tradition of privacy: the assumption that in one’s own house, one can live however one wishes, as long as one does not break the law or disturb the neighbours.

It has been observed, with truth, that many immigrants are natural conservatives, who believe in hard work, standing on one’s own feet, and the value of ancient institutions such as the monarchy. The fact that they want to come and make their lives here is a compliment to our way of life, and also a renovation of it, for it makes us more energetic.

The great-grandfather of the mayor of our principal city was a hafiz, someone who knows the Koran by heart. But does anyone think this makes Boris Johnson less British? Does anyone say we should get rid of him because he is in part the descendant of immigrants? Or of Mr Farage, because he is descended from Huguenot refugees?

The Conservative Party still holds Benjamin Disraeli, the first British Prime Minister of Jewish descent, in particular reverence and affection. It should stop being quite so frightened of immigrants.