The British government is significantly underestimating the likely impact of mass immigration on future population growth, according to an expert think tank.

Lord Andrew Green of Deddington, Chairman of Migration Watch UK, has questioned why the Office for National Statistics (ONS) is basing its new “principal population projection” on international net migration to England of 152,000 per year.

This would increase the population of England, the largest and most populous of Britain’s Home Nations, to over 60 million by 2032, well up on the 2016 estimate of 55.3 million, with the hyper-diverse, crime-ridden capital of London swelling to 10 million by 2035.

Staggering though these figures are, Lord Green believes they hugely underestimated the speed and scale of the changes England is undergoing, as average net immigration to the country is actually well in excess of 152,000 a year — “whether you take the average of the past five years (246,000 per year) or the average of the past ten years (213,000 per year).”

Study: Britons in Every Demographic Group Want Immigration Reduced https://t.co/nyFyJGW4Hx — Breitbart London (@BreitbartLondon) April 9, 2019

Writing in The Telegraph, the former diplomat and Royal Green Jackets officer said it would be “much more realistic to use what the ONS calls its ‘high migration scenario’ (based on net migration to England of 215,000 per year) which would see England’s population rise not by 4.8 million between 2016 and 2032 (as in the principal projection) but by 5.9 million” — a difference, he points out, of “well over a million people.”

“Time and again the government has underestimated projected population growth,” the cross-bench peer reminded readers.

“A decade ago they estimated that the UK population would not reach 64 million by 2017. In fact, by mid-2017, the UK population exceeded a record 66 million.”

Guy Verhofstadt: ‘Not Acceptable’ for UK to Limit Immigration After Brexit https://t.co/60QIRRedbF — Breitbart London (@BreitbartLondon) February 19, 2018

Lord Green warned that any attempt to deliberately “downplay the reality of rapid population” could only “backfire”, and that this latest ONS “discrepancy” would “further undermine public confidence in the authorities on immigration”.

“A poll published last year found that only 17 per cent of the public trust the government to tell the truth about immigration either all or most of the time,” he said.

Developments over the past few years suggest the public’s mistrust may not be entirely unjustified, as the governing Conservative Party have entered three general elections under two different prime ministers vowing to reduce net immigration “from the hundreds of thousands to the tens of thousands”, only for non-EU immigration — the only type of immigration which Britain can actually control, as long as it remains in the EU — to hit a 15-year high in the latest figures.

UK Migrant Boom: EU Migration Falls, But Non-EU Migration at 15-year High https://t.co/NQ4bRPJ4Qd — Breitbart London (@BreitbartLondon) February 28, 2019

Shortly after the Brexit vote ended his immediate political career, David Cameron’s Chancellor of the Exchequer and chief lieutenant George Osborne revealed that persistent failure to fulfil immigration promises was a feature, rather than a bug, of Tory government.

“Over the past seven years, the Government has not been able to reduce significantly the numbers of non-Europeans coming here — though we could,” he admitted openly in 2017.

“[N]one of [the Cabinet’s] senior members supports the pledge [to reduce immigration] in private and all would be glad to see the back of something that has caused the Conservative Party such public grief,” he revealed.

Follow Jack Montgomery on Twitter: @JackBMontgomery