A rapist has complained that he is being "ripped off" when he buys olive oil and tins of tuna or mackerel fillets in jail - after conducting a price comparison survey from his cell.
Adam Marchment, who was jailed for ten years in April last year for raping a 15-year-old girl and sexually assaulting a 14-year-old girl, said he was sick of paying higher prices than people pay on the outside, reports the Daily Mail.
The 26-year-old carried out "research: from his cell at HMP Parkhurst on the Isle of Wight - which now, along with HMP Albany is called HMP Isle of Wight - even getting a family member on the outside to check prices online and at major supermarkets.
He then compared the prices to how much items cost on the canteen list, which is supplied by DHL.
Writing in this month's edition of prisoners' magazine Inside Time, Marchment said: "Like many others, I am really starting to get frustrated by HMPPS (Her Majesty's Prison and Probation Service) responses to the many prisoners complaining about our privatised, over-priced canteen system."
The heavily-tattooed inmate said he "tested"' claims made by prison chiefs that it was 'not allowed to charge over the market recommended retail price", adding: 'I tested this theory and had a family member outside do some checks.
"On Princes.co.uk they state that the RRP for a tin of mackerel fillets in tomato sauce is £1.45, yet DHL sell them to us for £1.75.
"I also had a comparison website checked and none of the top supermarkets had the same item priced at over £1.40.
"In fact at most supermarkets you can get 4 tins for £5.
"A bag of Nescafe coffee original 150g, is £2.99, yet DHL sells this item to us for £3.99.
"Extra virgin olive oil is £1.99 for 500ml, but DHL sell us 250ml for the same price. Are you seeing the recurring pattern?"
He added: "DHL continue to rip us off and are getting away with it.
"It is about time HMPPS stopped ignoring this situation and realise that prisoners have access to the outside world and will question the utter rubbish they try to feed us."
Marchment, of Farnham, Surrey, was jailed for ten years at Guildford Crown Court in April 2016 after admitting one count of sexual assault on a 14-year-old girl in September 2015 and was found guilty of raping a 15-year-old girl in July 2014.
The court heard how police launched a manhunt for the rapist in October 2014 after he breached his licence conditions.
Marchment was on the run for more than a month, and even taunted cops on social media, putting a video called "Man on the Run" on YouTube bragging about how officers couldn't catch him.
Speaking on the video at the time - wearing sunglasses and a hoodie - he said: "Hello everyone, I'm Adam Marchment and as you all know I am a wanted man. I have now been on the run for 37 days.
"I've got a little message for Surrey, Sussex and Hampshire Police - "run run as fast as you can, you can't catch me I'm the Marchment man".'
He was caught soon after posting the video online.
Bosses at the HMPPS said that it was "mindful of the need to provide value for money to the taxpayer in all our contracted services".
It said, however, in a response to criticism over canteen prices in Inside Time that "all public sector prisons must operate a cost-neutral contract, at no cost to the public".
It stated that prisons "must use the National Product List (NPL) in offering items to prisoners, and is not permitted to charge over the market recommended retail price for any of the products sold".
A Prison Service spokesperson said: "Products sold through the prison canteen service are never higher than the manufacturer's recommended retail price."