Illegal migrants don't need to bypass the system - there is no system to bypass - Kwasi Kwarteng

Many, however, have come from countries we know very little about. They have been affected by unimaginable trauma in lands where violence and brutality are just a normal part of life.

Somalia, Rwanda, some of the Balkan states and much of the Middle East, from Iraq to Libya, have been the scene of ugly, bloodthirsty conflicts in recent years.

We have no idea about the history of violence in those countries, nor to what extent immigrants from those parts have been psychologically damaged by this.

I expect Rudakubana’s descent into pathological violence and cruelty is linked to a history, a memory, of this kind.

Even though he was born in Britain, we can’t tell how he was affected by the appalling violence, the genocide, in Rwanda which his parents lived through. This does not excuse him of guilt.

He made sick choices, but his background provides a context, without which we cannot begin to understand the crimes he committed last summer.

The scale of the problem can be measured by the sheer numbers that have come into the country. Both major parties, let’s face it, have failed on this.

From a net migration average of about 50,000 a year between 1950 to 2000, immigration into the UK exploded from the beginning of this century.

Last year we had a net figure of 900,000. Nearly ten times the “tens of thousands” I and many Conservative parliamentary candidates campaigned on in 2010 and subsequent elections.

The situation is arguably even worse with regard to illegal immigration. In this area, nobody knows the true picture.

Millions have come to these shores over the years, but nobody knows where they have lived, or what brutalities they have endured or, let’s not be naive, inflicted.

The causes of illegal migration are not difficult to work out. Civil wars around the globe, criminal traffickers on a scale never witnessed before and, above all, the internet and social media, where successful illegals migrants post picture of their wonderful, luxurious lives in the West- have all driven the push to come to places like Britain.

But, as in so many aspects of our national life, successive governments have not caught up with the times. Our asylum laws originated at the beginning of the last century.

They were designed to offer refuge to people feeling genuine persecution, such as Jews facing Tsarist pogroms in Russia, and the like.

Likewise, we offered protection to Jews fleeing Hitler and, most memorably in relatively recent times, to Ugandan Asians fleeing the racist brutality of Idi Amin.

The asylum system was not designed to provide succour for economic migrants. It is natural for people to want to better their lives, but the system is broken.

Many illegal immigrants are simply failed asylum seekers we have failed to deport.

This week we learnt that a study for Thames Water shows that 1 in 12 inhabitants of London is an illegal migrant.

In raw numbers, proportion represents 585,000 people. But the annoying thing is that we cannot know for sure. As the Home Office itself has said, there “is no officially recognised way of measuring how many illegal migrants are in Britain”.

Illegal migrants, let’s not forget, have simply bypassed the lack of any system whatsoever. These migrants have come to Britain, in flagrant defiance of the law, or any established process.

This is clearly a breakdown in the functioning of the state. If Britain is truly “broken”, nothing demonstrates this more clearly than our failures to curb illegal migration.