Has the UK seen the highest wave of immigration for nearly 1,000 years?

"The reality is that we are experiencing by far the largest wave of immigration for nearly 1,000 years."

Frank Field and Nicholas Soames, Daily Mail, 6 September 2012

In a comment piece in this morning's Daily Mail, MPs Frank Field and Nicholas Soames decided to turn to the history archives to compare current immigration levels with those of the past millennium.

But can we really compare immigration figures from today with any we might find in the Anglo-Saxon Chronicle?

Analysis

Anyone looking to tackle this claim from a statistical perspective will quickly run into difficulty because the Office for National Statistics (ONS) has only been collecting data on migration since 1964.

We can see from the ONS interactive graph on immigration, that the Daily Mail is right in claiming that there has been a boom since the early 1990s. We've experienced a plateau in recent months, but the levels are undeniably high.

However the level of immigration into the UK is only one side of the migration triangle, as people leaving the country can mean that the overall population may have fallen in spite of the new arrivals. To consider the overall impact that immigration is having on population numbers, we need to look at net migration.

Last year, net migration was 216,000, meaning that the UK gained over 200,000 people. Looking at the ONS interactive graph again, we can see that while net migration was more often than not negative for two decades after 1964, since 1998 the country has been gaining people at a significant rate.

So certainly, both immigration, and more importantly net migration, have reached higher pinnacles since the ONS began collecting data in 1964.

But in what sense can we say that were experiencing levels unheard of for nearly 1,000 years?

The problem is, that even if we did have official statistics showing immigration going back to the Norman conquest, the data wouldn't tell us a great deal.

Firstly, populations around the world have increased sharply over the past century: there are now simply more people around to migrate, meaning we could expect larger population shifts, particularly as technological advances have made travel easier.

The latest census figures estimate that in 2011, the population of England and Wales had reached 56.1 million, while the first official count of the population in 1801 was estimated at 9.3 million. 

Going back further is again hamstrung by the lack of good data, although historian Josiah Russell estimated a population of around 2 million in the British Isles in 1000 in his article 'Population in Europe'.

Of couse the same number of people arriving on these shores would have a different impact depending upon how many people were already inhabiting the UK, so to try to make such broad historical comparisons doesn't tell us a great deal about the consequences of population movements.

Conclusion

Although there are no official migration statistics that go back further than 48 years ago, it is quite possible that immigration, and indeed, net migration levels, are at their highest for nearly 1,000 years.

This wouldn't be surprising: there are both more people in the world and better connections within it than ever before.

However whether the claim tells us anything useful about migration is another matter. Given the vastly different population sizes involved in a 1,000-year comparison, the relative impact that immigration has is quite different.

For example, the previous 'peak' from 1,000 years ago brought 10,000 Normans to these shores - a drop in the ocean compared to recent levels, but hugely significant for the 2 million strong population at the time.

Update (14/09/2012):

Migration Watch have been in touch to provide us with some extra information on the source of this claim, which is drawn from a briefing they have published looking at other periods of immigration in British history, including that of the Huguenots in the 16th and 17th centuries and Jewish immigration in the 19th and 20th centuries. You can get further details about the sources used to make these comparisons here.