“We already send too few people to prison. Out of every thousand crimes committed in this country, we send 12 people to prison. If anyone can name a country that sends fewer than that to prison then I’d like to hear it.” Philip Davies MP, BBC Daily Politics, 12 May 2011

With Ken Clarke’s controversial proposals for the criminal justice system threatening to cause further divisions among the Coalition’s top brass, the debate on whether or not “prison works” has rumbled on.

While Full Fact has already grappled with the efficacy of custodial and community sentences, the Justice Secretary has argued that we don’t have the luxury of choice in the matter, calling the present system “unsustainable”.

However one prominent Conservative backbencher, Philip Davies, has suggested that this isn’t the case, and that on the contrary, the UK sends fewer criminals to prison than its international peers.

Appearing on the BBC’s Daily Politics last week, he challenged viewers to point to a country that locks up fewer than the 12 people per thousand crimes committed that he claimed were sent to jail in the UK.

Never one to baulk at such a gauntlet, Full Fact took up the case, and traced Mr Davies' figures back to piece of 2005 research carried out by think tank Civitas.

This used reported crime figures and prison population statistics from EU countries to calculate the proportion of offenders sent to jail. The UK did indeed lock up 12.7 people for every thousand crimes recorded.

However you don’t have to get too far into the report to discover that in fact there are several countries that send fewer people to prison per thousand crimes than the UK.

Sweden had the lowest ratio, committing 4.7 offenders to custodial sentences for every thousand crimes, while five other countries sent a smaller proportion of its criminals to prison. On top of this, Germany also sent 12.7 people to jail per thousand crimes.

However the 2005 report is now rather dated, and we have more up-to-date data available to us. So what picture emerges when we consider this?

Using the EU’s Eurostat database, we can see that in 2008 – the last year for which there is presently data – the UK actually had a slightly higher prisoner to crime ratio, with 17.8 criminal s locked up for every thousand crimes recorded.

This is close to the median among our European peers. Sweden remains the country with the fewest number of prisoners per thousand crimes at 4.9, while Spain sent approximately 31.6 offenders to jail for every thousand crimes.

But to complicate matters further, it is by no means clear that this sort of international comparison provides us with any useful insight at all. As we have pointed out before, international comparisons of recorded crime are notoriously unreliable, as different countries compile these figures in different ways.

In the UK alone, the methodology used to record crime has changed a number of times in recent years. On the continent, the amount of crime recorded can vary depending on at what point in the criminal investigation the offence is recorded. For example, while in England and Wales a crime is recorded when it is reported to the police, in Italy and Germany it is only counted after it has first been investigated. In Denmark, there aren’t even any set rules for how individual police forces compile their figures.

So while international analyses based on recorded crime should be treated with caution, taken at face value Mr Davies’ claim that only 12 criminals are sentenced to jail terms for every thousand crimes recorded by the police is not groundless, coming as it does from a 2005 study of the international data.

However a look at the more up-to-date information suggests that this number has risen slightly in the intervening years (during which time recorded crime has fallen in the UK). Furthermore, the UK has never had the lowest ratio of imprisonment to crime, as implied by Mr Davies, and in 2008 found itself near the mid-point of its European neighbours on this particular measure.