Violin from band who played as the Titanic sank to be auctioned for record-breaking price Wallace Hartley's violin, if proved authentic, will be auctioned on April 20 The final scientific tests are underway to prove its authenticity It is expected to sell for hundreds of thousands of pounds Hartley's fiance gave the instrument to him after their engagement The anonymous owner claims she retrieved the violin after his death Fateful night: If proved authentic, the violin of Wallace Hartley (pictured) will have survived the tragedy in which more than 1500 people lost their lives The violin believed to have belonged to the heroic band master who played as the Titanic sunk is set to sold at auction for a record price. If proved authentic, the violin of Wallace Hartley will have incredibly survived the tragedy in which more than 1500 people lost their lives in the Atlantic on April 15, 1912. The final extensive scientific tests are underway to prove its authenticity but experts believe it to be genuine. It is expected to fetch hundreds of thousands of pounds on April 20 when it is auctioned by Titanic experts Henry Aldridge and Son based in Devizes, Wiltshire. It has passed all other tests over the last seven years and the results of the last investigation are due early next month. A plan of the Titanic used in the inquiry into the doomed ship sold for a record £220,000 in 2011 but it is believed the instrument will exceed this price. The anonymous seller of the violin claims that Maria Robinson, Hartley's bereaved fiancé, retrieved the violin after his death. The instrument had been a gift from her. The fate of Hartley's violin has always been a mystery to Titanic scholars. All eight members of the band that gallantly played as passengers lined up for evacuation to the lifeboats perished in the disaster but the bodies of the band leader and two other musicians were pulled from the water by a search crew from the CS Mackay-Bennett and taken to Nova Scotia, Canada. Violinist John Law Hume from Dumfries in Scotland and bass player John Frederick Preston Clarke from Liverpool were laid to rest in Halifax but Hartley's body was repatriated to England and buried at Colne, Lancashire, the town where he was born and raised. Gift of love: Wallace Hartley, pictured front row, fourth from left with violin in the Bridlington Municipal Orchestra, was given the violin he played on that fateful night by his fiance Maria Robinson Newspapers at the time reported that Hartley was found fully dressed with his violin strapped to his chest. However, when the effects of Body 224 were itemised by The Office of the Provincial Secretary in Nova Scotia there was no mention of it. Other than his clothes and spare change he had only a ring, a pen, a silver matchbox, a gold cigar holder, a watch and chain, a collar stud, a pair of scissors and two pieces of correspondence. It was not among the possessions handed back to his father Albion Hartley who collected the body from the Arabic at Liverpool docks. The assumption has long been that the instrument was spirited away by someone involved in collecting the corpses. Now the instrument believed to be Hartley's is currently being handled by the leading Titanic memorabilia auctioneer Henry Aldridge and Son who hold every record set for items from the ship and are considered the world's leading authority on its artefacts. Incredible story of survival: The violin of bandmaster Hartley who played as the Titanic (pictured) sank, is set to sell at auction for hundreds of thousands of pounds They have so far spent many thousands of pounds seeking to establish beyond any doubt that the violin is the genuine article. A spokesman for the company declined to comment on the impending auction. But a source close to the sale confirmed: "It is the most iconic and important item ever connected to the Titanic to come up for sale. Leading Titanic memorabilia auctioneer Henry Aldridge and Son have so far spent many thousands of pounds to prove it was Hartley's violin We are talking about high six figures. There will be worldwide interest. All the tests have proved its authenticity so far. There is just one final test left and the results are due in early March. If that confirms the authenticity then it will be sold. The auctioneers have been thoroughly professional and painstaking over this. They have been on the case for seven years. Auctioneer Henry Aldridge said previously: "When I first saw it five years ago I was amazed. If I did not think that the probability was there I would not have bothered. The research is expensive business but because of the historical importance of this item the money is secondary. We cannot rush the scientists. During his research for The Band That Played On, a book that tells the story of all eight of the Titanic's musicians, top British author Steve Turner came across a collection of photographs purporting to show the violin, a leather case, and various sheets of music. He said: "I was suspicious at first but when I looked closely I could only conclude that this was the real thing or the result of an extremely elaborate and well informed hoax. I am convinced that it is genuine and impressed by the scope of the scientific and historical tests that have already taken place. I can't imagine anything more valuable connected to the Titanic. Hartley's fiance Miss Robinson moved to the Yorkshire seaside resort of Bridlington after his death but never married. She died alone in 1939. Among the supporting evidence that she retrieved the violin after his death is a 1912 diary where she had apparently drafted a letter to the authorities in Nova Scotia thanking them for acceding to her wish to have the violin sent to her. The draft letter in her diary reads: "I would be most grateful if you could convey my heartfelt thanks to all who have made possible the return of my late fiance's violin. May I take this opportunity to express my appreciation to you personally for your gracious intervention on my behalf. Mr Turner said: "When I checked the name of the provincial secretary for Nova Scotia it corresponded with what was written in the diary although Robinson had written F. Walthers instead of F. Mathers. The band played on: The band play on as the Titanic begins to sink in a scene from James Cameron's 1997 film version. All eight band members perished The most convincing thing about the violin, which was in a brown leather case with the initials W. H. H stamped on it, was the inscription on the tail-piece. It said: "For Wallace on the occasion of our engagement from Maria." This seemed not only to explain why she wanted it back so badly, and why it didn't automatically go to Hartley's parents, but perhaps why Hartley kept it with him in the water. Mr Turner also points out that the ink letters that were found on Hartley were near perfect and had not been affected by the sea. He said: "Because the violin was a gift from Maria to Wallace on their engagement it makes sense that she was the rightful heir rather than Hartley's parents. I wonder whether Hartley clung on to it so tightly because it was a gift from his wife-to-be. Otherwise he might just have let it go. If this turns out to be what everyone involved hopes and believes it is, I think it will; be the most expensive Titanic artefact ever offered for sale. It was not only once on the Titanic but it played a key role in the story. On top of that, it symbolises the love of two people.