LONDON (Reuters) -The red and white St George's Cross and the Union Jack flags have proliferated along streets across England in recent weeks in what supporters say is a campaign to show national pride, but others fear is part of growing anti-immigration sentiment. The flags have emerged during a politically charged summer in Britain that has been dominated by the subject of migration, with the YouGov monthly sentiment tracker showing that since the end of June immigration has overtaken the economy as voters' biggest concern. "It's our flag, we should be able to feel proud to fly it," said Livvy McCarthy, a 32-year-old bartender, as she walked past a pedestrian crossing in the Isle of Dogs, London, painted to resemble the English flag.