Both the UK and Poland are members of the European Union (EU). The EU allows people from any EU country to live and work in any other EU country.
Poland became a full EU member in 2004, which gave its citizens the automatic right to live and work in the UK and other EU countries. Because there were far more jobs in the UK than in Poland, and wages and living conditions were generally better here, a great many Poles (hundreds of thousands of them) migrated to the UK between 2004 and 2007.
A similar thing happened with British people in the early 1980s, when unemployment was high and a lot of UK manual workers went to Germany to look for work. This was depicted in the original ITV series of Auf Weidersehen Pet.
There aren't lots of Poles coming here any more, though - in fact, many of them are going home now, due to the economic situation in the UK getting worse and there being far fewer jobs available for them.
To the person who said:
"The bus companies could`nt get anyone to do the job before the Poles came. There`s your answer. Our young people don`t want to work, the Poles do."
That was because the bus companies were paying crap wages, not because nobody wanted to do the job!
Why would a British person want to earn some pitiful amount like £7 an hour to put up with abusive passengers and bad traffic, when they could earn double that amount as a train driver or a taxi driver?
If they put the wages up they'd get loads of British people applying (and I bet they DO now have loads of Brits applying, now that jobs are scarce elsewhere).
Poland is a poor country, so £7 an hour is actually really good by Polish standards. That's why you have all these Polish bus drivers.
I hate this stupid myth of "Poles being more hard working". If supposedly "lazy" Brits had the opportunity to travel to another country and earn four times their normal wage, I bet they'd be hard working too.