Whenever we think the barbarism in the world cannot get any worse, someone proves us wrong. This week the Saudis have tried to do it again: they plan to crucify Ali Mohammed al-Nimr, a juvenile.

Ali was just 17 when he was arrested on 14 February 2012. He was accused, first, of participation in an illegal demonstration, and second, of an ill-defined firearms offence. He does not dispute that he protested the persecution of his uncle, Shia Sheikh Nimr Baqr al-Nimr, who has also been sentenced to death for daring to demand democratic reforms.

When will the government learn that to cosy up to despots means that we are on the wrong side of human rights, and ultimately the wrong side of history? - Clive Stafford-Smith

No evidence has been produced on the firearms allegation, which he and his family strongly deny. He was initially held at a juvenile offender facility, but even then it seems he was tortured and forced to sign a confession.

Typical of the secretive world of Saudi Arabia, and its 'Specialised Criminal Court', the scope of his 'crime' has never been defined. He was sentenced to 'death by crucifixion' on 27 May 2014.

In early September, his family heard that his final appeal had already been heard, again in secret without bothering to tell Ali, and dismissed. This means that there is no legal obstacle to his death.

This is obviously a deeply emotive subject. My small boy goes to the local Church of England primary school, and it set me aback around Easter time when he came home talking about hammering nails into someone on the cross.

There has been a soupçon of progress over the past 2,000 years – apparently today they behead you first, and place you on a cross for three days so that everyone can appreciate what might happen to them.

There remains only the question of what we should do to demand that Saudi Arabia should not torture and execute juveniles for demanding democracy. In this regard, we might hope that our own government would promote human rights around the world. Sadly not.

The British government has a project called "Just Solutions International", one of those euphemisms that almost certainly covers up a plethora of wickedness. JSI is the "commercial arm" of the Ministry for Justice, and it "offers tried and tested products and services from one of the largest and most integrated offender management systems in the world."

One of the "just solutions" upon which they have embarked is to accept money to "conduct a training needs analysis for the Kingdom of Saudi Arabia prison service staff." What does this entail: How to torture a juvenile? How to affix him to the cross? How much will JSI be paid, 30 pieces of silver?

When Nigel Huddleston MP recently asked a parliamentary question about this project, the government tried to fob him off in a written response, saying that they could not withdraw their bid without severe financial penalties. That turned out to be false. UK Ministers had to correct the Parliamentary record this week, on September 16th: there were no "financial penalties."

The only reason for continuing with the bid is that "withdrawing at this late stage would be detrimental to [Her Majesty's Government's] wider interests." These wider interests seem to involve repeating the mistakes of history.

When will the government learn that to cosy up to despots means that we are on the wrong side of human rights, and ultimately the wrong side of history. The House of Saud has been sowing the repressive seeds of its own destruction for many years, and the longer it survives the harder it will fall – and the more angry and extreme will be its successor.

We must remind our elected representatives (who work for us) that we wish to stand up for decency, not for decapitation and crucifixion.

Clive Stafford Smith is director of the legal action charity Reprieve, www.reprieve.org.uk. Follow him on Twitter @clivess