L.A., London Production Firms Team on 'Great Train Robbery' Doc (Exclusive)

Chris Long, producer and occasional director of "The Mentalist."

Chris Long, executive producer of "The Mentalist," will direct the film based on interviews with one of the original gang members behind the infamous heist.

LONDON -- U.K. TV production banner Kowalski Television is teaming with L.A. production outfit Scallie Films to make a documentary using interviews with one of the most secretive members of the gang involved in the so-called "great train robbery."

One of the U.K.'s most infamous heists, involving the fleecing of the Royal Mail train in 1963 by a team of thieves who made off with millions of dollars, this August marks the 50th anniversary of the robbery.

STORY: Jim Broadbent to Star in BBC's 'Great Train Robbery' TV Movie

Kowalski Television managing director Simon Howley, whose credits include Life or Death for Discovery and Pirate Gold for National Geographic, was approached by a mutual friend of Gordon Goody, a key player behind the 1963 robbery, to tell the inside story of the heist and the full extent of his life of crime that spanned 20 years and accumulated millions of dollars.

Using interviews with Goody, the documentary is being directed by Brit Chris Long through his banner Scallie, the executive producer and sometime episode director of The Mentalist.

Long has secured The Mentalist castmember Owain Yeoman to do the documentary's voice work.

Long and Howley just completed the shoot and are now at the editing stage.

The documentary comes in the year that the BBC is bringing an all-star two-part TV movie The Great Train Robbery to BBC One commissioned by BBC Drama chief Ben Stephenson, BBC Drama controller and BBC One controller Danny Cohen.

Kowalski Television aims to develop projects from documentaries to dramas for both U.K. and U.S. markets.

It is currently developing projects with U.S. Special Forces, law enforcement agencies in the deep South, and the CIA.