Time Was is a time travel romance novella by British author Ian McDonald, published on 24 April 2018 by Tor Books.
Tesco has suspended production of charity Christmas cards at a factory in China after a six-year-old girl found a message from workers inside one.
Tesco said it was "shocked" by The Report , adding: "We would never allow prison labour in our supply chain. "
The supermarket said it would de-list the supplier of the cards, Zhejiang Yunguang Printing, if it was found to have used prison labour.The Pack of cards Cost £1. 50 from Tesco
In block capitals, it said: "We are foreign prisoners in Shanghai Qingpu prison China. Forced to work against our will. Please help us and notify Human Rights organisation. "
It asked whoever found The Message to contact Peter Humphrey, a British journalist who was himself imprisoned there four years ago.
Her father, Ben Widdicombe, said he first felt "incredulity" at discovering The Message , adding he first thought it was "some sort of prank".Florence Widdicombe, aged six, says finding The Message made her feel shocked
He added: "It could have ended up anywhere. And indeed we have many cards as all families do That are left over and we put them in a drawer and forget about them. There is an incredible element of chance in all of this That The Card was written, it got to us and we opened it on The Day we did. "
A Tesco spokeswoman said: "We were shocked by these allegations and immediately halted production at the factory where these cards are produced and launched an investigation. "
The supermarket said it has a "comprehensive auditing system" to ensure suppliers are not exploiting forced labour.
The factory in question was checked only last month and no evidence of it breaking the ban on prison labour was found, it said.
The retailer has not received any other complaints from customers about messages inside Christmas cards.'Very bleak life'
After the Widdicombe family sent him a message via Linkedin, Mr Humphrey said he then contacted ex-prisoners who confirmed inmates had been forced to work.
He then wrote the story.
Mr Humphrey told the BBC: "I spent two years in captivity in Shanghai between 2013 and 2015 and my final Nine Months of captivity was in this very prison in this very cell block where this message has come from.
He said the cell block of foreign prisoners has about 250 people in it, who are living a "very bleak daily life" with 12 prisoners per cell.
"They sleep in very rusty iron bunkbeds with a mattress which is no More Than about 1cm thick underneath," he said.
"In the winter it's extremely cold, there's no heating in The Building and in the summer it's extremely hot because there is no air conditioning.
"They get up around 5:30-6:00am Every Day they have to go to bed again at about 9. 30. "
"Everyone I know in there at the Time Was in there for very questionable reasons," he said. "I met so many people who I considered to be The Victims of wrongful imprisonment or at least reckless sentencing for minor offences. "A foreign inmate dries clothes at Shanghai Qingpu prison in 2006
Mr Humphrey said he believes those who wrote The Note "knew very well what risks they were taking and they were prepared to take this risk".
"They know very well That if they're caught, they will be punished. They could be punished for example by losing some merit points or having some kind of deprivation of some of their food allowance.
"They could be punished by sending them to solitary confinement for a month or something like That where conditions are fairly harsh. "
"They resorted to the Qingpu equivalent of a message in a bottle, scribbled on a Tesco Christmas card," he said.
In 2012, Julie Keith from Portland, Oregon, discovered by a prisoner who said he was forced to manufacture the Halloween decorations she had purchased.
And in 2014, Karen Wisinska from Co Fermanagh in Northern Ireland , reading: "Our job inside The Prison is to produce fashion clothes for export. We work 15 hours per day and the food we eat wouldn't even be given to dogs or pigs. "