The campaign against Chris Grayling's ban on prisoners being sent books was backed by prison staff themselves today, as doubt was cast on a key plank of the justice secretary's argument.
The general secretary of POA, the trade union for prisoner workers, insisted staff had never had a problem dealing with the parcels being sent in to jails, casting doubt on Graylings assertion that it would not be "secure or practical" to allow parcels to be sent to prisoners.
The comments came as Gareth Davies, former governor of Pentonville prison, branded the book ban "barbarous".
They also coincide with an intervention in the debate by the chief inspector of prisons, who branded the policy a "mistake".
Steve Gillan, general secretary of the POA, told Politics.co.uk that Grayling's insistence that prison guards could not scan parcels for drugs or other contraband was ridiculous.
"For decades prison officers have dealt with parcels. They searched them," he said.
"The reality is it was never really a problem. Now and then people tried to smuggle drugs in that way. But as professional prison officers we found these items.
"The majority of these books and magazines that came in didn't have any drugs in them at all.
"People have been having their books sent in for 20, 30 years and now all of a sudden it's become a big issue for the secretary of state."
The comments cast doubt on Grayling's argument, made in Politics.co.uk earlier this week, that a ban on parcels across the prison estate needed to be imposed for security reasons.
The Ministry of Justice tried to bolster its case by sending images to the press of contraband hidden in gifts sent to prisoners from friends and family, such as Weetabix with a chamber inside them for drugs.
Gillan's comments are particularly damaging because they come from a figure who otherwise supports Grayling's Incentives and Earned Privileges scheme.
"I agree with the secretary of state on stopping Sky TV and letting prison officers have control of the incentive and privilege scheme," he said.
"We agree with some of what the secretary of state has done, but not the book issue – that's never really been a problem."
Gillan's comments come as frustration against the book ban policy grows among current and former prison staff.
In a letter to the Times today, former Pentonville prison governor Gareth Davies described the "deliberate deprivation" of books as "barbarous".
He said the policy "filled me with shame that such a thing was being perpetrated in British people's interests".
The rules, which came into force last November, "shows a system that has discarded an important principle by which I lived for 26 years, that prisoners are incarcerated as punishment but not for punishment", he added.
"Reading is essential in the educative processes. These have been acknowledged for many years as a key element of rehabilitation. What on earth is the minister thinking?"
In a related development, chief inspector of prisons Nick Hardwick said the book ban policy was a result of ministers trying to control prison policy from the centre.
Hardwick told the Independent that the broad objectives of the incentives scheme were "sound", but added: "The problem in this case… is trying to micro-manage this from the centre, with the centre describing very detailed lists of what prisoners can and can't have.
"I think that's a mistake. I think that once the policy intention is clear, how that's implemented should be left much more to the discretion and the common sense of governors, so that they can reflect the needs of their particular prison population."
The intervention from prison professionals comes amid a huge backlash against the policy from leading authors, including Salman Rushdie, Martin Amis and Alan Bennett.
A Change petition set up to make the justice secretary revise the policy has now acquired over 19,000 signatures.