It's a by-product of exporting lots of people to the countries that were once known as 'the Dominions' (ie. self-governing parts of the Empire) during during the last century, and then offering their grandchildren easy work permits and fast-track citizenship.
And why not? It's just like a family looking after it's own first, is it not? There are Ozmates, Kiwis and SuidAfrikans a plenty in many industries in the UK - often filling skills shortages (therefore adding to UK plc and HM Government's coffers).
It's the airlines not providing enough opportunites for locals to progress that we should be moaning about, rather than Brits with funny accents....