It must make sense. You come from a country rich in everything, and which economists everywhere say will one day realise its potential; you take a job here, in a country rich in skills and know-how, but where few natives want to do menial jobs. You earn hard currency, then you go back home, buy property and watch it rise in value as your country's economic boat comes in.

You might also educate yourself or your offspring while you are here, a move which back home will eventually help the economy along.

Is this the thinking now motivating the migration to Britain of people from so-call BRIC economies - Brazil, Russia, India, and China - which economists predict are set to prosper in coming years, partly at the expense of the western world?

Brazilian marketing graduate Plaudemir Varjao, 45, from Sao Paulo, who first arrived in Oxford in 2001, said: "Yes and no. Really, money is the motivation. It's not easy to get money. In Brazil, many people work for less than £100 a month - if they can find a job.

"Here in Oxford, many Brazilians work 14 hours or more a day and earn more than £1,000 a month. And they send money home to their families.

"Often they have more than one job - for example, a cleaner in the morning and a waiter during the day."

He should know. He is a director of Core Cleaning, a domestic and commercial cleaning service now employing eight people, six of whom are from Brazil, with the remaining two from Poland.

But so far, the growth of the Brazilian economy has worked against its migrant workers, the Rial having risen against the pound from 6 Rials to the pound in 2001 to just 3.5 Rials now.

All the same, Brazilians still come here in ever greater numbers - despite Home Office rules of entry changing so fast that it is difficult to keep up with them.

Mr Varjao's own story is revealing of Home Office barriers to gaining work here, apparently kept just high enough to ensure a manageable number of legal immigrant workers arriving here to do the jobs that many British-born people do not want.

He explained: "You may work 20 hours a week on a tourist or student visa. But if you want to change your status you must go back to Brazil and start again. You cannot change it when you are already here."

He added: "I came here and met my wife, Rosmarie, in 2001. She was originally Brazilian, but is now a UK citizen. On our return from honeymoon in Portugal I was told that I had to return to Brazil within ten days and start the process of entering UK, to live here permanently."

But in spite of such barriers, Mr Varjao apparently has no axe to grind against UK immigration procedures. He said: "I think they are fair."

Now - with a rented house in Summertown and two children, Francesca, two, and Saskia, seven - he is co-director, with Portugese-speaking businessman Mark Rose, of Core Cleaning - a company which he says always pays its employees above the minimum wage and works as a vehicle to help other Brazilians establish themselves in Oxford.

The company has the motto: "We do more than just clean."

He said: "It is not easy. Paperwork is always a problem. I must make sure that everyone who works for the company has the proper papers and is allowed to work the hours."

The company, which he says has a turnover of about £40,000 a year and numbers the letting agency Finders Keepers among its customers, charges from £10 an hour. But he says the market is extremely competitive, not least because of competition from (possibly) illegal workers.

Mr Varjao has nothing but praise for Oxford's Ethnic Minority Business Service (EMBS). He himself took an English course there and encourages all employees to do the same. Now he is taking an evening course there in book keeping.

He said: "Obviously, a person cannot be a good worker here if they cannot speak English. Last week, I helped an employee who had problems when he filled out an insurance form for his car incorrectly. He did that because he did not understand the English."

Like most of his workers, Mr Varjao sends money back to Brazil. In his case, the money helps to support his 17 year-old daughter, Mayara.

He said fondly: "She does not know yet what she wants to do. Once, she wanted to become a doctor. Now she wants to become an investment banker."

Our conversation took place in a smart Banbury Road office near his home, where Mr Varjao rents space by the hour when necessary, keeping overheads to a minimum.

And how does Oxford look from the point of view of a Brazilian immigrant? He admitted to having been shocked by some of the goings-on he witnessed at a home for the elderly where he obtained one of his earliest jobs in Britain.

Then, being football-mad, there was the time he was a waiter at Oxford United. A co-worker accused him of working illegally and a guest at the club turned out to work for the Home Office.

And how about success stories? Had he heard of anyone earning enough money here to go back home and found a business empire?

Sadly no. In fact, he remembered the tale of a Brazilian exploited by his own countrymen. He had sent home money for years to buy a fishing boat - which did not exist, as he learned when he finally returned home.

It's a hard world for some, but Mr Varjao, for one, appears to be winning against the odds and helping others do the same. He now plans to stay here and build up the business. We wish him luck.

To contact Core Cleaning, call 01865 339412, or email: info@corecleaning.co.uk.