Migration Observatory also says estimate of net migration could break previous record of 320,000 set in 2005 when figures for 2014 are published on Thursday

The number of people living in Britain who were born abroad is likely to exceed 8 million for the first time when the latest official figures are published this week, according to an Oxford University thinktank.

The Migration Observatory says the number of non-UK born residents in Britain has increased steadily over time and the current trend means that Thursday’s figure for 2014, published as part of the latest set of quarterly migration statistics, will top the figure.

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It also says the latest estimate of net migration – the flow of migrants in and out of the UK – could break the previous record of 320,000 set in 2005, shortly after eight eastern European countries, including Poland, joined the EU.

“In the last quarter’s data net migration was estimated to stand at 318,000 – just 2,000 below the highest level previously recorded in 2005 … This is the figure that is used to assess the government’s target to reduce net migration ‘from hundreds of thousands to the tens of thousands’. It could go down in Thursday’s data, or it could go up and break the previous record,” the observatory’s latest commentary says.

It says that both figures taken together will show that the basic message is that migration is higher than it was a few years ago.

The number of non-UK born residents gives only a partial picture of recent migration and integration trends, because it is a cumulative figure stretching back over decades.

A better yardstick to watch for on Thursday could be the number of people who live in Britain but who retain a non-British nationality.

The previous set of figures showed that there were 7.78m non-UK born residents in 2013, but only 4.9m who did not have British nationality. Poles were the most numerous, with 726,000.

The Office for National Statistics says that 3.23m people born abroad have British nationality.

The Migration Observatory says the proportion of the UK population born abroad is broadly comparable with that of other states that were EU members before 2004. Six countries, including Austria, Ireland and Sweden, had larger proportions, and nine, including Italy and Portugal, had smaller proportions.

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“The prevalence of migration to the UK is therefore by no means unprecedented by European standards,” it says.

The thinktank also acknowledges that the 8 million “landmark” figure for the non-UK population is somewhat arbitrary, and adds that the biggest challenge in interpreting the figures is that there is no optimum size for the UK’s population or for the number of migrants living in the country.

“From an economic perspective immigration brings both costs and benefits and affects different people in different ways, leaving no objective method of deciding what the ‘right number’ of migrants is. Different demographic, economic and political arguments can be marshalled in favour of either increasing or reducing immigration, and reasonable people will disagree,” it says.

It points out that although David Cameron has described UK population growth as unsustainable, the Scottish government has set an objective of increasing population growth, arguing that rural and coastal communities are unsustainable without it.