The Bank of England has already said it's asked its supplier to work on "potential solutions" to the issue of animal fat in its new £5 notes.
The BoE confirmed using a trace of animal fat, called tallow, in its new £5 bank notes last week and promptly caused a bit of a stir.
Hi Annie, there is a trace of tallow in the polymer pellets used in the base substrate of the polymer £5 notes.— Bank of England (@bankofengland) November 28, 2016
The announcement has caused discontent among some vegetarians and religious groups. And now the Rainbow Cafe in Cambridge has put up signs saying: "We cannot accept the new £5 note as it contains animal by-products!"
The owner of the cafe, Sharon Meijland, told the BBC that her "whole business is based around not having anything like that on the premises". Since the posters went up on Wednesday, no customers have complained, she added.
But the Australian pioneer of the polymer bank note has said it's "absolutely stupid" that vegetarians and vegans are up in arms about the note containing animal fat.
Professor David Solomon spoke on Australian radio station 2GB earlier in the week and said: "It's stupid. It's absolutely stupid." He added that there were "trivial amounts of it in there".
More than 125,000 people have signed a petition to remove tallow from the notes, which are the first polymer notes in circulation in the UK.
The petition states: "The new £5 notes contain animal fat in the form of tallow. This is unacceptable to millions of vegans, vegetarians, Hindus, Sikhs, Jains and others in the UK. We demand that you cease to use animal products in the production of currency that we have to use."
The Bank of England has said it didn't know the animal material was used in the making of the note.
"We are aware of some people’s concerns about traces of tallow in our new five pound note. We respect those concerns and are treating them with the utmost seriousness," it said. "This issue has only just come to light and the Bank did not know about it when the contract was signed."