Jack The Ripper was a three man gang - The Final Solution with Stephen Knight (1980)

BEWARE - gory and explicit documentary.
Fantastic book, thank you Stephen, you're a legend.

Ignore the Wikipedia entry on this book which has been 'hacked', as usual when the elite are criticised, in an attempt to discredit Stephen Knight's excellent work. Stephen went on to write the brilliant 'The Brotherhood' one of the all time most incisive books on freemasonry.
Joseph Sickert, aka Joseph Gorman, says that Albert Victor's mother, Princess Alexandra, introduced Walter Sickert to her son in the hope that Sickert would teach Albert Victor about art. Gorman claims that Albert Victor met one of Sickert's models, Annie Elizabeth Crook, a Catholic shop girl, at Sickert's studio at 15 Cleveland Street, London. They had an affair, he says, and married in a secret ceremony with Sickert and Annie's friend, Mary Jane Kelly, acting as witnesses. Gorman alleges that Albert Victor and Annie's daughter, Alice Margaret Crook, was born on 18 April 1885, and that Albert Victor settled Annie and Alice into an apartment in Cleveland Street. In April 1888, Gorman continues, Queen Victoria and the British Prime Minister Lord Salisbury discovered Albert Victor's secret. Gorman accuses Salisbury of ordering a raid on the apartment because he was afraid that public knowledge of a potential Catholic heir to the throne would result in a revolution. Gorman claims that Albert Victor was placed in the custody of his family, while Annie was placed in the custody of Sir William Gull, who certified her insane; she spent the next 30 years drifting in and out of institutions before dying in 1920.
http://www.amazon.co.uk/dp/0586046526
Meanwhile, Gorman alleges, Kelly was looking after the daughter, Alice, both during and after the raid. Gorman asserts that at first Kelly was content to hide the child, but then she, along with her friends Mary Ann Nichols, Annie Chapman and Elizabeth Stride, decided to blackmail the government. Gorman accuses Salisbury of conspiring with his fellow freemasons, including senior policemen in the London Metropolitan Police, to stop the scandal by staging the murders of the women. Gorman says Salisbury assigned the task to Gull, who lured the four women into a carriage individually where Gull murdered them with the assistance of coachman John Netley and Sir Robert Anderson, Assistant Commissioner of Scotland Yard. Gorman claims a fifth victim, Catherine Eddowes, was killed accidentally in a case of mistaken identity because she used the alias Mary Ann Kelly and was confused with Mary Jane Kelly. Gorman alleges that Netley tried to kill the young Alice twice but after the second unsuccessful attempt several witnesses chased Netley, who threw himself into the Thames and drowned. Gorman completes the story by saying that Alice lived well into old age, later becoming Walter Sickert's mistress, and that Alice and Walter Sickert are his parents

Who really was Jack the Ripper? Was he a solitary assassin lurking in the shadows of gaslit London? Or was Jack the Ripper three men: two killers and an accomplice? In this work the author investigates all aspects of this strange case shrouded in mystery and misconception. The discovery of the murders is described by the men who were there, and evidence reveals that the hitherto unsolved Ripper murders were in fact a culmination of a full-scale cover-up organized at the highest level of government.

Reading this, Sir William Gull makes for the perfect ripper psychologically. Not only was he a Physician (with extensive medical knowledge) but as a number of chilling recollections from his life prove, he was an avid supporter of vivisection and was capable of extreme acts of cruelty. Throw the spanner of 'Freemasonry', the espionage of a 'secret society' and the ominously convenient association of some of England's most powerful people to Sir William into the pot and you have a thrill a minute read.