A widow who was left £15million by a high-rolling gambler has launched a multi-million pound lawsuit against his family – claiming she is owed up to £385million more. Ruanne Dellal says her husband Jack was worth at least £400million when he died and the £15million left to her was an ‘absurd presentation’ of his true wealth. The former beauty queen has launched a High Court claim against his relatives, in which she claims the property tycoon must have given away vast chunks of his fortune in secret deals to his family. Scroll down for video . Lawsuit: Jack Dellal left his whole estate to wife Ruanne, but she is suing after discovering that it amounts to just £1.7million . Daughters: Mrs Dellal is suing six of her husband's children, including Gabrielle, left, and Jasmine, right . Mrs Dellal, 61, whose own assets have been valued at £41.5million, says she is owed a ‘reasonable provision’ following the death of the legendary gambler. Her late husband, known as ‘Black Jack’, was a regular at the gaming tables of casinos in Mayfair and Monaco and gambled £1.7million in a single night in 2006. His family dispute his widow’s allegations and the true extent of the tycoon’s wealth will now be scrutinised by the High Court, which will assess Mrs Dellal’s claim that she has been short-changed. She claims six of his children are the supposed beneficiaries of his alleged secret handouts. Siblings Lorraine, Diane, Gabrielle, Jasmine and Rowan were named along with son Guy, the father of Agent Provocateur lingerie model Alice Dellal. His grandson Alex and elderly sister Violet were also named. Yesterday, they failed in a bid to persuade a judge to throw out her claim before it could come to trial, setting the scene for a potentially explosive court battle. Mr Dellal, who was friends with celebrities including Sir Mick Jagger, was notoriously secretive about his financial dealings but is said to have gambled millions every year, regularly winning or losing up to a £1million a night. He died in October 2012, aged 89, and left his entire estate to Mrs Dellal, his second wife, with nothing to his six adult children from previous relationships as he said he had already made provisions for them. Mrs Dellal, a former Miss South Africa, received £15.4million and he also put £20million in a trust fund for their two children, now aged 15 and 12. Son: Guy Dellal, pictured with his wife Andrea, is also being sued by his stepmother over his father's will . Granddaughters: Guy is the father of model Alice Dellal, left, and shoe designer Charlotte Dellal, right . But she claims his fortune appears to have shrunk mysteriously between his 2006 will which named her as his sole beneficiary and his death six years later. Mr Dellal, who was born in Chorlton, Manchester, to Iranian émigré parents, made a fortune in textiles, merchant banking and property and his wealth was once said to top £1billion. Jack Dellal was the son of immigrants from Baghdad, and he started his career as a humbile textile dealer in his home city of Manchester. He became a multi-millionaire after starting a small banking business called Dalton Barton, which he sold to the bank Keyser Ullmann in 1972 for £58million - more than £700million in today's money. Mr Dellal used the proceeds of the deal to set up Allied Commercial Holdings, which he used as a vehicle for property dealings for the rest of his life. In 1989, he made a vast profit from the purchase of Bush House on the Strand in central London, which was the headquarters of the BBC World Service. Allied Commercial bought the building for £55million in 1987, and sold it on to Japanese firm Kato Kagaku for £130million just two years later. His final big deal came with the sale of the Art Deco Shell-Mex House, overlooking the Thames, which raked in a £150million profit when it changed hands in 2007. He had a son and four daughters from his first marriage to a former Israeli air stewardess, which ended in divorce, and two daughters from another relationship. He married his second wife in 1997 and transferred assets worth around £56million to his six eldest children shortly after that wedding. By 2007 the couple’s marriage was in trouble and they each consulted two of Britain’s leading divorce lawyers, Raymond Tooth and Sandra Davis. Records of those meetings, revealed to the High Court, were said to show Mr Dellal did not dispute he was worth £400million. The couple did not divorce, but Mrs Dellal claims her husband began funnelling huge amounts of money into trusts for his children without her knowledge, and had a £50million ‘secret stash’ hidden in an account. In his written ruling, High Court judge Mr Justice Mostyn said Mrs Dellal had argued a ‘strong’ case that her husband had access to ‘very considerable resources’, but said there was little evidence he had given it to his children in secret. He said: ‘It goes like this. If Jack was very rich, and if his estate appears to have mysteriously shrunk, then the money can only have gone to his blood family. There are no other candidates.’ Mr Dellal’s family asked the judge to throw the case out as they said she cannot prove he gave money to them. They also argued Mrs Dellal’s wealth meant there was ‘no prospect’ of the court awarding her any more money. She owns an £8.5million mansion in Regent’s Park, central London, a £3million townhouse in Mayfair, the couple’s £5million home in Hampshire, a £1.1million house in Cape Town in South Africa, cars, jewellery and art worth almost £6million and has investments in the Middle East worth £26.5million. Grandson: Art dealer Alex Dellal, pictured with his wife Elisa and their son Jack, is the son of Guy . She claims her fortune has been ‘somewhat diminished’ recently, although Mr Dellal’s relatives argued that was down to her own mismanagement. Mr Justice Mostyn said it would be unfair to dismiss Mrs Dellal’s case without further scrutiny of her late husband’s finances. No date has yet been set for the case to be heard.
Jack Dellal left his entire estate to wife Ruanne but it was worth just £15.4m .
She claims he was worth £750m and gave his fortune away to his children .
Mrs Dellal has been given the right to sue her in-laws by High Court judge .
'Black Jack' once gambled £1.7million away in a single night .