But, according to The Sun last week, her family understood she would be saved from serving the rest of her sentence after being pardoned by President Abdel Fattah el-Sisi.
The paper reported that the president, who can issue pardons to prisoners as part of Egypt’s Revolution Day celebrations, was expected to announce her release last Saturday.
On Monday, the paper reported that the pardon had been withdrawn, with the British Embassy in Cairo informing her mother there had been a “mistake”.
Ms Plummer’s local MP, Karl Turner, has since said it was “disappointing” that the story had been published without having been confirmed “through official channels”.
But Rachel Plummer, her sister, defended the newspaper, and said the Foreign Office had said they were 95% certain she was on the pardon list.
In a message posted on Twitter that included Mr Turner’s Twitter handle, she wrote: “Hi all, as a family we need to set the record straight regards to Laura’s pardon.
“We were told by the Foreign Office who read out an email to my mother that they were 95% certain that Laura was on the pardon list, then we were contacted by Laura’s solicitor Mohamed Osman, confirming that she had been pardoned.
“The Sun followed the same information we did and have been with us throughout this awful nightmare from start to finish.
“They’ve offered us support at each stage and to suggest they went on a speculative rumour is wrong and unfair.”
The shop worker was arrested at the airport on October 9 last year when she flew into the Red Sea resort of Hurghada.
Her family have said she was taking the painkiller, which is legal in the UK but banned in Egypt, for her Egyptian partner Omar Caboo, who suffers from severe back pain, and had no idea what she was doing was wrong.
A Foreign Office spokeswoman said: “At no point did Foreign Office staff advise Laura’s family that we believed she would be imminently released. We continue to recommend they obtain updates on Laura’s legal situation from her lawyer.”
Mr Turner said he had been in regular contact with officials in Egypt and the UK, and that the latter had “only ever maintained throughout that they have received no such information from the Egyptian authorities”.
In a statement posted on Twitter, he said: “It is clear to me that any suggestion that she was to be released by the Egyptian authorities was merely speculative rumour and it had not been confirmed by the British Foreign Office.
“It would be highly unusual for the Egyptian Government officials not to notify Foreign Office officials here in the UK if they had in fact intended to release a British citizen from detention in Egypt.
“It is disappointing to say the very least that this story was ever published without it being confirmed through official channels.”