At a hotel in Mozambique, a waiter poured my tea. He held the pot slightly too high so that it cascaded over the cup, the saucer and my hand. He stared at me helplessly, murmured, "Oh shit," but continued pouring until I dropped the crockery in agony.

The manager subsequently explained that the hotel was trying to provide local employment rather than relying on Zimbabweans and South Africans. It was just going to take a bit of time to get them up to standard, so she hoped guests could be patient.

I was reminded of this after the Employment minister Chris Grayling called on Pret a Manger to take on more British workers. The HR director of the sandwich chain replied nimbly that it operated in a global market and that the diverse staff gave it a cosmopolitan feel.

Of course this is true. One of the great pleasures of living in London is the extraordinary range of nationalities. I've just been chatting to a Colombian office cleaner, an Egyptian shopkeeper, a Turkish dry cleaner, a Nigerian student and an Australian barman. We have had the best of all worlds. We tingle with pride at our marvellous enlightened, non-racist outlook, and profit from it too, rejoicing that weekends, holidays and VAT appear to mean nothing.

I will not forget the former Labour minister Patricia Hewitt explaining the workforce-without-borders policy of the last government. Immigration was really not an issue, she told a group of us who were journalists on The Daily Telegraph at the time. Think how handy it will be for domestic staff, she said.

And then came the Polish builders. A generation owes its basements and bathrooms to Poland. I cringe at my airy recommendations to liberal friends: "Really, I have these maaarvellous Poles! They never take a break! They send the money home."

Who would return to the old half- days, builders listening to Radio 1, endless tea, directions to the toilet. No politician questioned the effect of the Polish plumbers on the UK workforce. That would be racist. The only media champions of the old working class were Julie Burchill and Rod Liddle. And then came the summer riots.

Now we are reluctantly considering the cost of our maaarvellous Poles, it is time to take responsibility. Those who rail against the Government for its heartless cuts overlook their own record as employers. We have been doing up a house in Norfolk, not notably in the front-line for immigration, but with many migrant workers in the fields. The builders are local, and thus rooted in the community. Some of them are fathers and sons and I like recognising the local genealogy of the names.

They work for a firm with the family name blazoned proudly on the vans. The renovation has taken a bit longer than it would in London, because the builders like to see their families at weekends, or take part in community sport. If you want a Big Society, it helps if people feel they have a stake in their neighbourhood.

No one wants to return to the bland England of the 1970s, and I do think the multinationalism of London makes it the best city in the world in which to live. But it is at a price. We have to find ways to get our young unemployed skilled up. We need businesses to provide apprenticeships. But how can we exhort Pret a Manger to do it, when we won't employ Brits ourselves?

Sarah Sands is deputy editor of the 'London Evening Standard'