Marcel Duchamp is considered one of the great artists of the 20th century, but was his greatest achievement - Fountain - a urinal bearing the signature R. Mutt, the work of someone else?

The original Fountain has long been lost, and for many decades forgotten, but in the 1950's became such a talking point again that Duchamp decided to manufacture up to a possible 17 copies - one of which stands proud, under glass, in the Tate Modern.

Earlier this century a poll of 500 art historians voted it the most significant art work of the 20th century, for the questions it raises about art and the artist, but although the importance of 'Fountain' in the history of art is undisputed, is it certain the artist was, in fact, Duchamp?

And if it wasn't him, then who was it?

Join the dots, and the paint brush of history seems to point at the Baroness Elsa von Freytag-Loringhoven - a truly free spirit and radical artist, who Duchamp called 'the future'. The smoking gun is a letter written in 1917 by Duchamp to his sister Suzanne, stating "One of my female friends" had submitted the urinal as a sculpture to the exhibition, "the pseudonym Richard Mutt".

True, false, or just a fascinating theory... its one that throws an interesting light over one of the most significant works of the 20th century.

Steve Punt dons galoshes and heads for the nearest convenience.

Producer: Sara Jane Hall.

One afternoon in July 1953 Father Henryk Borynski, a Polish priest living in Bradford, took a telephone call. His housekeeper heard him say "OK, I'll go". He put on his hat, and his coat and left. He was never seen again.

Many Poles fled to the United Kingdom during World War II and settled in Bradford. With the onset of the Cold War they became exiles, unable to return to Poland. In his sermons, Father Borynski was an outspoken critic of the Soviet system and many believed he could have been a victim of communist agents operating in England.

Steve Punt investigates, following leads and opening Secret Service files, to find out what might have happened to Father Borynski.

Producer Neil McCarthy.

A piano tuner discovers a hoard of gold coins carefully concealed inside a piano. Whoever hid it there is a mystery. Radio 4's very own Inspector Clouseau Steve Punt is on hand to piece together the clues. His detective trail leads him on a journey through Victorian music circles, the Freemasons, bankruptcy, and Shredded Wheat packets as he works out who stashed the gold.

Producer Neil McCarthy.

Steve Punt returns as Radio 4's very own private detective.

In this tenth anniversary edition, Steve's called in to investigate the unlikely disappearance of American and Russian nuclear weapons - with assistance from best-selling thriller writer Frederick Forsyth.

At first, Steve's sceptical - surely no nuclear power could actually lose possession of weapons capable of causing Armageddon. But as his investigation gathers pace, the story starts to becomes rather disturbing.

From an H-bomb lost over Savannah, Georgia to a cache of so-called 'suitcase nukes' which rumours suggest could still be stashed in modern day Moldova, Punt weighs up the evidence - with a little detour via Dorking...

Producer: Laurence Grissell.

What is it?

The sounds generated by mating fish? The US government? Or even the evolution of humans to hear electromagnetic waves... Steve Punt, BBC Radio 4's Mulder and Scully combined, turns his analytical ears to The Hum - heard by people, all over the world, tonight.

For some of those who hear it, it's unpleasant, even distressing, for others simply mysterious.

The Hum has been reported as far back as the 1960's, when people in Bristol first brought it to the attention of the local council. They never found out what caused it.

From Surrey to the ionosphere, he examines afresh some of the most common theories - with leading experts: is it the sounds created by fish, as recorded by neurobiologist Dr Andrew Bass; or the noise of seismic waves as discussed with expert Dr Lucia Gualtieri of Columbia University, New York; might it be a whole range of potential ear problems as suggested by Mark Williams at the Tinnitus Clinic; tall buildings - given short shrift by South Leeds Life editor, Jeremy Morton; electromagnetism - considered by science expert Roland Pease; and last, but definitely most 'X-files' of all, HAARP, a US military research station, now run by Bob McCoy of the University of Alaska - a theory poo-pooed by national security journalist Sharon Weinberger.

He also touches base with the creator of the World Hum website, Dr Glen MacPherson, who is trying to keep an online record of this phenomenon - most commonly described as a diesel engine in the distance.

Producer: Sara Jane Hall

Music sourcing: Danny Webb.

Steve Punt continues his investigations as Radio 4's very own private detective.

In 1939, just before the outbreak of World War II, the reclusive actress Ada Constance Kent disappeared from the village of Fingringhoe in rural Essex. Despite her cottage being searched on several occasions in the intervening years, her skeleton was only discovered in the bedroom in 1949. Was it her... where had she been in the intervening years... and was she really the person everyone thought she was?

Steve Punt interrogates the witnesses and assesses the evidence.

Producer: Paul Kobrak.

Steve Punt returns as Radio 4's very own private detective.

Punt travels to Paris to investigate the suspicious death of celebrated writer Émile Zola. Zola died in 1902 from carbon monoxide poisoning caused by a blocked chimney. At the time, the authorities reached a verdict of accidental death. Subsequently, evidence has emerged that Zola's death may have been murder.

Certainly Zola's role in France's notorious Dreyfus Affair made him many enemies. But as Punt discovers, the case is far from clear cut. For one thing, carbon monoxide is a very unusual way of murdering someone. Punt summons the experts and weighs up the evidence.

Producer: Laurence Grissell.

On Christmas Eve 1975, former Spitfire pilot Peter Gibbs took off from the unlit airfield on the Isle of Mull and never returned.

It was a moonless night and having just finished dinner with his girlfriend at the Glenforsa Hotel, it seemed a bizarre and impetuous act.

Then Gibbs’ body was discovered on a hillside, but the plane was nowhere to be seen and the story began to get stranger.

Punt heads to the Mull to investigate, but with every piece of evidence the mystery deepens.

Was Gibbs attempting an illicit flight to Northern Ireland, was he trying to fake his own death, or was it something in creepy Room 14 that was to blame?

As he tries to disentangle myth from reality, Punt hears fishy tales from a suspicious local diver, unearths the original pathologist and scrutinises the man who watched Gibbs vanish into the night.

Producer: Sarah Bowen

Steve Punt turns Private Investigator and tries to crack the case of the missing Cézanne masterpiece 'Auvers sur Oise'.

The painting was stolen from the Ashmolean Museum in Oxford whilst the city celebrated the millennium, and has not been seen since.

His search takes him from the crime scene to the Mayfair art world, via leads at Scotland Yard and sightings on a pub wall in Coventry.

With a watchful eye for any Mr Big who may be behind a painting reportedly "stolen to order", Punt PI enters the murky world of stolen art. But how close can he get to the stolen Cézanne?

Producer Neil McCarthy

Steve Punt returns with a brand new series of investigations - starting with the unsolved murder of major Hollywood director William Desmond Taylor in 1922.

Taylor was one of Tinseltown's biggest names - until he was shot dead in his bungalow in February 1922. Despite a multitude of suspects, Taylor's killer was never caught.

Producer: Laurence Grissell