Migrants will help to swell population of England by two London-sized cities within 50 years

The independent House of Commons Library is predicting that by 2056 there will be an extra 17million people  -  taking the total to 67.9million.

More births, people living longer and, more significantly, continued mass immigration will fuel the unprecedented growth in numbers.

Capital: By 2056, England will need two cities the size of London to cope with new migrants

The research came as an influential group of MPs demanded urgent improvements in the Government's methods of counting the population, claiming that it is 'not fit for purpose'.

A research paper produced by the Commons library says: 'The estimated population of London in 2006 was 7.5million. Making a straightforward calculation, the population in England will increase, between 2006 and 2056, by 2.3 times the current population of London.'

Based on current assumptions, it would mean the number of households in England increasing by 11.2million.

It is also likely to place enormous strain on public services, such as schools and hospitals.

Conservative MP James Clappison, who asked the library to complete the research, said: 'For somebody starting work today, they will experience population growth over their lifetime of two cities the size of London.

'What sort of quality of life are they going to have if there are 17million more people in England alone?'

Separate research by Karen Dunnell, the National Statistician, revealed the huge role immigration plays in UK-wide population growth, as compared with birth and death rates.

Net migration  -  the amount immigration adds to the population after subtracting emigration  -  is running at 190,000 a year.

But Mrs Dunnell's research shows that, until Labour came to power, 'natural change'  -  people living longer or having more children  -  was the main reason for Britain becoming more crowded.

Between 1992 and 1996, when the Tories were in power, natural change added 582,604 to the population of the UK. Net migration and other factors, such as the number of Forces personnel living in the UK, added only 143,112.

But, between 1997 and 2001, a huge change took place as the new Labour government adopted an 'open door' immigration policy.

Natural change added 416,471 to the population, and migrants and the other limited factors 532,652.

From 2002 to 2006, it was even more dramatic, with natural change adding 528,429, and net migration 932,999.

MPs on the Treasury select committee say today that the International Passenger Survey  -  which plays a central role in estimating international migration  -  is 'not fit for purpose'.

It surveys only a small number of travellers and, in the past, some ports were not even covered.

MPs also say short-term migrants are being excluded from official figures, leaving local councils short of funding.

Committee chairman Michael Fallon said: 'Reliable population estimates are fundamental for allocation of funding for public services.

'Our democracy is dependent on accurate, independent statistics. It is essential that when we consider important migrants granted UK citizenship since Labour came to power national issues we can rely on the data that is provided.

'It is now impossible to estimate accurately the UK population today.

'Unreliable statistics make planning impossible. We call on the Government to improve the population count as a matter of urgency.'

Tory immigration spokesman Damian Green said: 'This is a damning report.

'After 11 years in power, the Government has still failed completely to set up systems which allow them to measure immigration numbers.

'No wonder they can't control immigration when they don't know how many people are in this country.'

Earlier this week, the Daily Mail revealed that the population of England and Wales has shot up by more than a million in only three years in a boom on a scale not seen for a century.

Foreign workers were at the heart of the increase, according to the Government figures, which showed that numbers had reached 54,348,000.

The Home Office said it was introducing electronic border controls, a points-based visa system and would take into account any pressures on public services reported by its new Migration Impacts Forum when deciding the numbers allowed in.

A spokesman said: 'Projections like these are proof that we are right to be carrying out the biggest shake-up to the immigration system for a generation.

'Centre-stage is our new Australian points system which means only those we need can come to work or study.'