Items belonging to robbers Ronnie Biggs and Bruce Reynolds, who both died in 2013, are for sale at a Northamptonshire auction house.
They include a watch and a ring worn by Biggs in the robbery, as well as £1 and 10 shilling notes from the £2.6m haul.
An ignition key and petrol caps from getaway vehicles and a length of wire used to alter railway signals are also being sold off.
Bruce Reynolds planned the attack, at Mentmore Bridge in Buckinghamshire, on an overnight mail train travelling from Glasgow to London on 8 August 1963.
The gang of 15 wearing helmets and ski masks, made off with a then-record haul, equivalent to £40m in today's money.
Train driver Jack Mills was struck over the head during the robbery and never worked again. He died in 1970.
Reynolds evaded capture for five years and spent 10 years in jail. Biggs, who died aged 84 in December 2013, believed the British public saw him as a "loveable rogue".  He was sentenced to 25 years jail but escaped and fled to Brazil.
Memorabilia from the 1963 Great Train Robbery is being sold at auction.