In recent years, the number of Muslim prisoners has increased dramatically. Ministry of Justice figures show a rise from 6,571 in 2004 to 12,255 a decade later, meaning that Muslims now account for almost 15 per cent of all inmates.

In high security jails, the figure is higher still — one in five; while in one Category A establishment, almost half are Muslims.

Taken on its own, the disproportionate numbers of Muslims being jailed is in itself cause for concern (Muslims comprise roughly 5 per cent of the population of England and Wales).

But what is particularly worrying the authorities is the potential it offers for radicalisation.

As the number of Islamist extremists locked up for terror offences increases, so they are finding fertile ground among fellow prisoners. Indeed, it is claimed that some are deliberately getting custodial sentences so that they can target this pool of disaffected young men.