Despite the fact that one in 20 pre-school children in Britain is thought to be mixed race, and "bi-racial" people are the fastestgrowing ethnic group, those who monitor the country's ethnic make-up have been slow to respond. Until now, forms have stuck largely to the basic black, white or Asian descriptions. Britons who do not fit those categories - 400,000 at the last count - were part of a rapidly expanding "grey area".

But that is about to change. This year's official census, the forms for which go out on Monday, includes the new categories of white and black Caribbean, white and black African, white and Asian, and an "any other mixed background" category. It will also include Asian British and black British for the first time.

This is a significant widening of the scope of the census, which only began to monitor ethnic origin in 1991 after decades-long opposition to the move weakened. That year, mixed-race people were asked to tick "the group to which they considered they belonged" - in some cases effectively denying part of their identity - or to tick "other ethnic group" and squeeze complex details into the section provided.

But the numbers ticking the "other" category proved a problem for statisticians, who couldn't use it to identify trends. A four-year consultation followed and the result was a near-doubling of the ethnic group choices, from nine in 1991 to 16 this year.

Chris Myant from the Commission for Racial Equality said: "The challenge was to try to find a compromise between the UK's increasing diversity on one hand and the need for statisticians to have a limited number of categories to work with on the other."

Official figures on Britain's mixed population are expected to increase when the revised census forms are returned at the end of this month and when, as planned, the new categories are extended to all monitoring bodies.

A spokesman for the Office for National Statistics said: "A lot of youngsters who might have been described as black will now be described as mixed race." Mr Myant adds: "This is an important move. Many people have an identity put on them by society, whether it's black or white. This will let them define themselves."

But he believes there is a danger in reaching wildly positive conclusions about the growth of the mixed-race population and improved race relations. He said: "People are forming relationships across ethnic divides which tells us that racism is weakening. And there is an increasing willingness by people who are the product of those relationships to embrace that mixture.

"But nobody should exaggerate that. There may be a surface politeness in Britain, but the knives are still out."

"I used to be classed as 'other'"
Olivia Mercado, 26, lives in Peckham and works for an investment bank in Canary Wharf. Her father is Puerto Rican and her mother is British.
"I always used to have to tick the 'other' category on forms. There was never any way for me to express what I was," she said. "It felt insulting because 'other' suggests that you are inferior to everyone else.

"I think having a mixed section is a good idea, otherwise where do you fit in? Some people might expect me to classify myself as black, but I wouldn't tick black on a form because I'm not - I'm part Hispanic, which is different.

"I'm not saying there should be a category specifically for me. All you want is a description which allows you to be defined by yourself instead of by somebody else.

"From a cosmetic point of view being mixed-race makes you stand out in a crowd. I like looking exotic. People always try to guess where you are from because it's not immediately obvious."

Labelling can be divisive
Writer Helen Kolawole, 31, lives in Westbourne Park. Her father is Nigerian and her mother is English.
She said: "I have mixed feelings about the change. I am not dogmatic about labelling myself as mixed race because I think it can be divisive. In black communities there have been advantages to having lighter skin. I am also worried that the results will be held up by those who want to promote Britain as a perfect multicultural melting pot where racism no longer exists. Well no, that just isn't true.

Ms Kolawole said she had not been satisfied with ethnic categories on previous forms."In the past I sometimes ticked 'black other', but then I thought, what does that mean?" she said. "Other times I ignored the section in silent protest. I thought, 'If you are not going to provide a space for me I'm not going to fill in your form.'

"It's good that they've chosen the term 'mixed', which is better than half-caste and more open than mixed-race, which implies there are only two races. I've always defined myself politically as black. People look at me and see a black face and so I am treated as a black woman. It doesn't matter to them that my mother is white.

"In the past some mixed people have felt pressured to act either black or white. They don't so much now because there are so many more mixed kids around. Mixed children just don't raise eyebrows any more."

"Extending the categories is good"
Neil Noronha, 24, lives in Brockley and works for an advertising agency in Soho. His father is from Goa in India and his mother is part Portuguese, part English and part Indian.
He said: "At university most people stuck in the their own racial groups. The Asians hung out with Asians and the Greeks with Greeks. It was incredibly cliquey but I tended to hang out with everyone.

"I don't know if it's because I'm mixed. If my Asian friends wanted to ask a white person a question, they would come and ask me to do it.

"I see myself as Asian. My Asian friends do treat me differently, though. I've got green eyes and people always say stuff about them, and how I look different.

"I see being mixed as an advantage. It means you can fit in anywhere rather than not fitting in at all. People think if you are mixed you are unsure of who you are, but I've never had that problem. It's a good thing the categories have been extended. People are quite happy for you to tick one box and say, 'That's where you belong.' They want to categorise you. But it's a bit more complicated than that."

Neil Noronha, 24, lives in Brockley and works for an advertising agency in Soho. His father is from Goa in India and his mother is part Portuguese, part English and part Indian.
He said: "At university most people stuck in the their own racial groups. The Asians hung out with Asians and the Greeks with Greeks. It was incredibly cliquey but I tended to hang out with everyone.

"I don't know if it's because I'm mixed. If my Asian friends wanted to ask a white person a question, they would come and ask me to do it.

"I see myself as Asian. My Asian friends do treat me differently, though. I've got green eyes and people always say stuff about them, and how I look different.

"I see being mixed as an advantage. It means you can fit in anywhere rather than not fitting in at all. People think if you are mixed you are unsure of who you are, but I've never had that problem. It's a good thing the categories have been extended. People are quite happy for you to tick one box and say, 'That's where you belong.' They want to categorise you. But it's a bit more complicated than that."