What's the impact of migration on the UK economy? Photo: Getty
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Are migrants good for the UK economy?

Analysing two apparently contradictory studies that have been published about the impact of migration on the UK economy.

Two studies about the impact of migration on the UK economy have been published which – if media reports are to believed – appear to contradict one another. A closer reading of these reports, however, shows that in fact they come to very similar economic conclusions. Even so, from reading them it is possible to suggest very different approaches to migration policy.

One study by Professor Robert Rowthorn led to headlines such as: “Further proof of damage created by immigration” and: “How mass migration hurts us all”.

The second study is a paper published by Lineskova and others in the latest issue of the National Institute Economic Review which led to headlines such as: “Reducing immigration would slow UK economy and lead to tax rises” and: “Cameron’s migration cap would leave Brits poorer and taxes higher

So clearly the two reports have created space for some news outlets to pick their own truth. But what should we make of these different studies – and what do they contribute to our understanding of the impacts of migration on the economy?

Long-term impact on GDP

Both studies look at different annual net migration scenarios in the future to provide a picture of the long-term impact of migration on GDP and GDP per capita. The future level of net migration (that is, the difference between immigration and emigration) determines the size and age structure of the UK population.

As shown in Figure 1, if all other things remain equal, a higher level of net migration is expected to lead to a larger UK population (see complete explanation here).

But migrants also tend to be younger than the overall UK population and net migration is also likely to decrease the “dependency ratio” – an assessment of the number of people of working age compared to the number of people of retirement age. For instance, Rowthorn suggests that the dependency ratio will be 3.5 percentage points lower with annual net migration of 225,000 compared to an annual net migration of just 50,000 (Rowthorn defines the dependency ratio as the number of people 65 years of age and above per 100 persons aged 15-64). Figure 2 presents the 15-64 years old population of the UK under different assumptions about net migration.

Rowthorn suggests that, given a set of assumptions about employment rates and labour productivity: “GDP per capita is 3% higher in 2087 with high migration than with very low migration”.

The paper by Lineskova and others looks at two scenarios: net migration of 200,000 and a lower migration scenario, which assumes that net migration is reduced by around 50% – close to David Cameron’s migration target of less than 100,000. They find that by 2060 GDP per capita would be 2.7% lower under the lower migration scenario.

Given the impact of net migration on the size and age structure of the UK population it comes as no surprise that both studies conclude that higher net migration will be associated with a higher level of GDP and GDP per capita.

Long-term fiscal impacts

The two studies also look at the long-term potential “fiscal implication” – the impact on UK government finances – of migration to the UK. Rowthorn also looks at the short-term fiscal impact of migration. Rowthorn scrutinises previous analysis from the Office for Budget Responsibility which suggests that lower levels of net migration will lead to higher public sector net debt to GDP (see Figure 3). While Rowthorn does not contest the validity of the OBR estimates, he underlines the high levels of uncertainty related to these estimates.

The paper by Lineskova and others suggest that under the lower migration scenario to “keep the government budget balanced, the effective labour income tax rate has to be increased by 2.2 percentage points”. Again, this refers to estimates for 2060.

Both studies come to similar conclusions – that lower levels of net migration will impose greater pressure on national debt over GDP. This effect is just the result of faster ageing of the population with lower levels of net migration, and corresponds with standard economic thinking.

Why the different implications? There is agreement on the general economic effects of higher net migration in both studies: that conclusion is that higher levels of net migration lead to higher GDP per capita and lower net debt as a share of GDP. Where there is disagreement is about the need or desirability of higher net migration.

Social impacts

The Lineskova makes a straightforward economic argument from this about the benefits of migration in maintaining an age structure which supports economic growth. They do not venture into providing policy prescriptions and accept that their analysis does “not take into account the potential social impacts of higher migration”.

Rowthorn, however, emphasises that it may be preferable to have lower levels of migration even at the expense of faster ageing. He suggests that the levels of migration required to increased GDP per capita or lower future public debt are so high that their social impacts may outweigh the positive economic benefits. He points to potential problems such as overcrowding of public facilities (including schools, hospitals, roads), limited supply of housing and strain on natural resources (for example water) as additional reasons for preferring lower levels of migration.

This goes back to the essence of the migration debate in the UK. Economic estimates are important, but limited in that they cannot resolve important judgements about the type of society people want. These preferences over the “sort of place we want to live in” can drive people’s views and choices on migration just as much as the “pure” economic factors.


Carlos Vargas-Silva does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

This article was originally published on The Conversation. Read the original article.

Carlos Vargas-Silva is a Senior Researcher at the Migration Observatory at the University of Oxford.

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Inside Big Ben: why the world’s most famous clock will soon lose its bong

Every now and then, even the most famous of clocks need a bit of care.

London is soon going to lose one of its most familiar sounds when the world-famous Big Ben falls silent for repairs. The “bonging” chimes that have marked the passing of time for Londoners since 1859 will fall silent for months beginning in 2017 as part of a three-year £29m conservation project.

Of course, “Big Ben” is the nickname of the Great Bell and the bell itself is not in bad shape – even though it does have a huge crack in it.

The bell weighs nearly 14 tonnes and it cracked in 1859 when it was first bonged with a hammer that was way too heavy.

The crack was never repaired. Instead the bell was rotated one eighth of a turn and a lighter (200kg) hammer was installed. The cracked bell has a characteristic sound which we have all grown to love.

Big Ben strikes. UK Parliament.

Instead, it is the Elizabeth Tower (1859) and the clock mechanism (1854), designed by Denison and Airy, that need attention.

Any building or machine needs regular maintenance – we paint our doors and windows when they need it and we repair or replace our cars quite routinely. It is convenient to choose a day when we’re out of the house to paint the doors, or when we don’t need the car to repair the brakes. But a clock just doesn’t stop – especially not a clock as iconic as the Great Clock at the Palace of Westminster.

Repairs to the tower are long overdue. There is corrosion damage to the cast iron roof and to the belfry structure which keeps the bells in place. There is water damage to the masonry and condensation problems will be addressed, too. There are plumbing and electrical works to be done for a lift to be installed in one of the ventilation shafts, toilet facilities and the fitting of low-energy lighting.

Marvel of engineering

The clock mechanism itself is remarkable. In its 162-year history it has only had one major breakdown. In 1976 the speed regulator for the chimes broke and the mechanism sped up to destruction. The resulting damage took months to repair.

The weights that drive the clock are, like the bells and hammers, unimaginably huge. The “drive train” that keeps the pendulum swinging and that turns the hands is driven by a weight of about 100kg. Two other weights that ring the bells are each over a tonne. If any of these weights falls out of control (as in the 1976 incident), they could do a lot of damage.

The pendulum suspension spring is especially critical because it holds up the huge pendulum bob which weighs 321kg. The swinging pendulum releases the “escapement” every two seconds which then turns the hands on the clock’s four faces. If you look very closely, you will see that the minute hand doesn’t move smoothly but it sits still most of the time, only moving on each tick by 1.5cm.

The pendulum swings back and forth 21,600 times a day. That’s nearly 8m times a year, bending the pendulum spring. Like any metal, it has the potential to suffer from fatigue. The pendulum needs to be lifted out of the clock so that the spring can be closely inspected.

The clock derives its remarkable accuracy in part from the temperature compensation which is built into the construction of the pendulum. This was yet another of John Harrison’s genius ideas (you probably know him from longitude fame). He came up with the solution of using metals of differing temperature expansion coefficient so that the pendulum doesn’t change in length as the temperature changes with the seasons.

In the Westminster clock, the pendulum shaft is made of concentric tubes of steel and zinc. A similar construction is described for the clock in Trinity College Cambridge and near perfect temperature compensation can be achieved. But zinc is a ductile metal and the tube deforms with time under the heavy load of the 321kg pendulum bob. This “creeping” will cause the temperature compensation to jam up and become less effective.

So stopping the clock will also be a good opportunity to dismantle the pendulum completely and to check that the zinc tube is sliding freely. This in itself is a few days' work.

What makes it tick

But the truly clever bit of this clock is the escapement. All clocks have one - it’s what makes the clock tick, quite literally. Denison developed his new gravity escapement especially for the Westminster clock. It decouples the driving force of the falling weight from the periodic force that maintains the motion of the pendulum. To this day, the best tower clocks in England use the gravity escapement leading to remarkable accuracy – better even than that of your quartz crystal wrist watch.

In Denison’s gravity escapement, the “tick” is the impact of the “legs” of the escapement colliding with hardened steel seats. Each collision causes microscopic damage which, accumulated over millions of collisions per year, causes wear and tear affecting the accuracy of the clock. It is impossible to inspect the escapement without stopping the clock. Part of the maintenance proposed during this stoppage is a thorough overhaul of the escapement and the other workings of the clock.

The Westminster clock is a remarkable icon for London and for England. For more than 150 years it has reminded us of each hour, tirelessly. That’s what I love about clocks – they seem to carry on without a fuss. But every now and then even the most famous of clocks need a bit of care. After this period of pampering, “Big Ben” ought to be set for another 100 or so years of trouble-free running.

The Conversation

Hugh Hunt is a Reader in Engineering Dynamics and Vibration at the University of Cambridge.

This article was originally published on The Conversation. Read the original article.