GETTY Donald Trump’s plan to build a wall between the US and Mexico has attracted criticism

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But is he crazy or do walls serve a useful purpose in an age of failing states and mass migration? And if walls work then shouldn’t we have some in Europe? As we hear that net migration into the UK is back to record figures maybe it’s time to start getting those brickies busy. I’ve just come back from China and walked a section of its famous Great Wall. Snaking over mountains for hundreds of miles, it is an impressive building achievement as everyone knows but what is a little surprising is that sections of it are short, sometimes just 15ft tall.

Europe needs a Great Wall too

An angry warrior with a ladder could easily climb over it. The same is true if you visit sections of Hadrian’s Wall in Northumberland. But that’s not the point. These ancient walls weren’t built to stop a few fearless tribesmen but to halt a problem all too familiar to us today: mass migration. Chinese and Roman emperors invested vast fortunes in creating an obstacle to halt huge crowds of economic migrants travelling in wagons and on horseback and funnel them through fortified checkpoints.

GETTY Ancient walls were built to stop mass migration

You definitely can’t heave a wagon over the Great Wall of China. But is there a place for old-fashioned walls in a high-tech age? The Israelis certainly think so. Their Green Line Wall runs for 430 miles in the West Bank and has dramatically cut the number of suicide bombings and assaults by Palestinian terrorists. In Northern Ireland Peace Walls have successfully countered inter-communal violence between Protestants and Catholics. In Europe it is true that since the collapse of the Berlin Wall Europeans have been busy dismantling barriers and until recently you could travel for hundreds of miles across eastern and central Europe without encountering any barbed wire or checkpoints. Such were the joys of the passport-free Schengen Area, claimed the EU, but that has all changed with the eruption of mass migration from the Middle East and North Africa. When German Chancellor Angela Merkel invited hundreds of thousands of migrants to her country she forgot to ask the permission of the smaller countries they had to march through to reach Germany. She assumed they could be forced to agree after the fact.

Migrant Crisis: Mass exodus from the migrant camp continues Tue, October 25, 2016 Hundreds of migrants are continuing to arrive in Europe as they flee the scenes of chaos and brutality of the Islamic State in the Middle East. Play slideshow 1 of 224

But the Austrians said “No!” They ignored the diktats of the EU and erected their own secure fences to stop the flow of immigrants as did other neighbouring countries, including Hungary, Serbia and most importantly Macedonia. These physical obstacles backed up by security forces stopped the flow dead – so much so that Greece complained of having to host thousands of migrants stuck on their territory. Such has been the destabilising effect of hundreds of thousands of Muslim immigrants entering strongly Christian countries that Austria this week just narrowly avoided voting in the first far-Right head of state in Europe since 1945. Unless the EU gets a grip of the situation and starts erecting more effective barriers along the southern borders of Europe then European populations will start voting for ever more extreme leaders. That firm barrier should also mean naval vessels in the Mediterranean that return migrants to their points of departure, not just rescue and help them claim asylum in Europe.

GETTY Europeans have been busy dismantling barriers since the collapse of the Berlin Wall

Spain already has an autonomous enclave in Morocco at Ceuta and the EU could fund more such walled secure areas along the North African coast where intercepted migrants could be housed and ultimately returned to their own countries or safer neighbouring states. The flow needs to be reversed for the good of their own countries otherwise the drain of minds and talents will leave homelands the poorer for it. Anyone who has recently travelled to France by ferry or train will have noticed the increasingly fortified character of Calais where fences have helped reduce the flow of illegal immigrants into Britain. This is our Great Wall and – with or without Brexit – we need it to remain tall and strong and if necessary extend it. Immigration has made Britain, the USA and Europe rich and dynamic but it needs to be managed and controlled. Americans know that and many Latinos, who have lived and worked legally for years in the US, agree with Mr Trump and his determination to build a wall along its Mexican border.

GETTY Greece complained of having to host thousands of migrants stuck on their territory