The Central Bank of Seychelles keep these notes as archives and they are not to be sold.
"If someone comes to the bank to change one of his old banknotes, the bank will exchange it for a 50 rupees note," adds Tirant.
Today 50 Rupees is worth about £2.50, but the note that is to go under the hammer at Duke's of Dorchester in Dorset on October 15 has an estimate of £200.
Timothy Medhurst, from the saleroom, said: "This is a very collectable item for obvious reasons.
There are also those who believe it was just an unfortunate error; however, another note in the series appears to carry the word "scum", implying it was deliberate.
All pictures are presented by third parties by thier good will.
(Seychelles News Agency) - What seems to be a much sought-after collector’s item, in the form of a 50 Seychelles rupee banknote, believed to feature the word “sex” secretly written behind a portrait of the Queen of England, has been auctioned, fetching a little over £100 more than the estimated winning bid.
(Seychelles News Agency) - Back in the 1970s, the Seychelles archipelago in the Indian Ocean formed part of the British Empire, until it got its independence in 1976.
At that time, there was a 50 rupee banknote (equivalent of ) with the portrait of Queen Elizabeth II of Great Britain, with her head shown near some coconut trees.