This machine stamps the metal cover with a design.

With an almighty thud the tree slides vertically along the 'V' cut and buries the sawn end into the ground only two feet from where it started, ending up perfectly upright, as if it had never moved.

Messrs Denton and Denton will sell it to whoever's need is greatest, whoever's purse is deepest, whoever will most recklessly mortgage his future, whoever is of its desirers the most pound-puissant.

The use of algorithms in policing is one example of their increasing influence on our lives. And, as their ubiquity spreads, so too does the debate around whether we should allow ourselves to become so reliant on them – and who, if anyone, is policing their use.