Exactly 34 years ago this week, a small balding man with a droopy moustache and a comb-over took to the witness stand in the wood-panelled splendour of Court Two at the Old Bailey.
When Bertie Smalls finished giving his testimony, the seven defendants he had incriminated began singing from the dock.
After a rendition of the blues ballad "Whispering Grass", the ad hoc choir pointed their fingers into the shape of guns and sang the Dame Vera Lynn classic: "We'll meet again, don't know where, don't know when."
To those seated in the public gallery of Britain's most famous criminal court it was a bemusing and surreal spectacle. But for Smalls, the gang of armed robbers sitting in the dock and the members of Scotland Yard's Flying Squad watching proceedings, the meaning of the performance was chillingly clear.
After some 15 years at the top of London's close-knit fraternity of hardened robbers and gangsters, Smalls, a 38-year-old career criminal with a big house and more than a dozen bank jobs to his name, had just achieved the dubious distinction of becoming Britain's first supergrass by giving a comprehensive account of a robbery on 10 August 1972 at a branch of Barclays in Ilford, east London, that netted £237,000 – a record amount at the time.
Upon his arrest, Smalls told his interrogators: "I can give you every robber in London."
Between February 1974 and April 1975, evidence and assistance from Smalls to police and the Crown Prosecution Service secured the imprisonment of 28 of his former colleagues for a total of 414 years, with sentences ranging from five to 18 years.
In return, the rotund informer received an unprecedented (and never to be repeated) deal giving him immunity from prosecution but life-long opprobrium among his one-time underworld brethren. The price on Smalls' head, put at £1m during the late 1970s with signatories including the Kray twins, was lifted yesterday with the news he had died at the age of 72 while still under the protection of the police.
The death of Smalls, who survived for more than three decades despite being a target for gangland vengeance and who died at his unremarkable Victorian semi in Croydon, south London, went unmourned among those who still adhere to the "honour among thieves" doctrine of never ratting on your fellow felons.
Although a cliché, it has long been an article of faith among the nation's "gentleman" gangsters that Smalls single-handedly destroyed an unwritten code with his betrayal. Perhaps unsurprisingly, "Smalls" has become gangland slang for a "snout" or informer.
As "Mad" Frankie Fraser, the former East End gang member who served 42 years in prison before writing a best-selling autobiography, put it: "There is no doubt that 'grasses' such as Bertie Smalls and other filth like him deserve to be shot like the sick dogs they are."
But for others, the passing of the first major league British criminal prepared to divulge the full list of his associates is a salutary echo of an era when the unscrupulous antics of both fast-living criminals and hard-drinking police were the stuff of daily life rather than television fantasy.
It was a time when fugitive villains with big hair and wide lapels headed for sanctuary in unheard of overseas locations with names such as Torremolinos and robberies were carried out with elaborate plans involving gang members dressed as City bankers to distract staff.
The arrest of Smalls in 1972 for a string of highly-lucrative robberies conducted since the late 1960s coincided in particular with an inglorious episode in the history of the Yard where bribe-taking, occasional collusion and the practice of "verballing" or fabricating evidence was rife among detectives.
Such was the extent of bad practice that when Sir Robert Mark became Commissioner of the Metropolitan Police in 1972, he felt obliged to publicly remind his officers of their duties. In his inaugural address to his colleagues, Sir Robert said: "A good police force is one that catches more criminals than it employs."
The finger of suspicion was pointed very clearly at the Criminal Investigation Department (CID) and its most elite unit, the Flying Squad, responsible for targeting armed robbers and high-profile gangsters but at the time better known for the uncomfortably close relationship between some of its members and their prey.
It was no coincidence in this era of bent coppers that one of the most high profile corruption prosecutions of the early 1970s was against Commander Ken Drury, the head of the Flying Squad, also known by its rhyming slang nickname as the Sweeney. Drury was convicted of five corruption charges and jailed for eight years.
In this context, the arrival of Derek Creighton "Bertie" Smalls was a godsend.
His Wembley Mob, a hardened corps of criminals based in north London which was responsible for a succession of armed robberies throughout the late 1960s, was just one of about a dozen similar gangs operating in the capital at the time.
Compromised and often outwitted by what many misguidedly considered to be the swashbuckling and daring masterminds of big set-piece bank robberies, the Flying Squad saw the number of raids in London rise from 380 in 1972 to 734 by 1978. It reached 1,772 by 1982.
The testimony of Smalls showed how much damage could be done by a high-level "stoolie".
The number of robberies in the area of London where the Wembley Mob had been most active fell from 65 to 26 in the year after their arrest and imprisonment.
Chief Superintendent Jack Slipper, the famous detective whose pursuit of the Great Train robber Ronnie Biggs became the stuff of Yard legend, said after the Old Bailey trial in February 1974: "Smalls is the greatest weapon the police have ever had against the underworld. He will have to spend the rest of his life with a £1m price on his head because so many people want to get even with him."
It was not the status that Smalls would have expected a few years before his arrest. Born in the East End, he rose through the ranks of the underworld to become a leading practitioner of the "epic" robbery – a well-planned hit on a bank or similar target with high risks and high rewards.
By 1972, the Wembley Mob were one of the most prolific crews in the capital, living in big houses and driving fast cars. Shortly before the raid on the Barclays branch in Ilford, which ultimately proved his downfall, Smalls was paid £10,000 (about £200,000 today) for his part in a robbery on a savings bank in Brighton.
The "Ilford job" carried all the trademarks of the gang's meticulous methods. Through an informant, they learnt that the bank received large deposits consisting of the takings of a Tesco supermarket and that when these large amounts arrived, the security van was preceded by a red Mini presumed to be sent to inform the manager. This enabled the robbers to pick the appropriate day to secure the largest amount of cash.
After recruiting two employees of the security van company, Smalls sent one of the robbers into the bank dressed as a City worker, complete with pin-stripe suit and an umbrella, to write a cheque to distract staff while the van approached. The raid went "smoothly" with the corrupt security guards handing over the money and the robbers escaping in seconds.
Within five days, most of the gang had fled abroad to lie low. Smalls travelled by ferry from Newhaven to Dieppe before taking a train to Paris and then flying to Torremolinos, the Spanish resort whose popularity with Britain's fugitives was already beginning to earn the Costa Del Sol the nickname of Costa Del Crime.
Ironically, it was the efforts of another informant, who gave police the names of every member of the Wembley Mob, that led to Smalls' arrest. He was caught in November 1972 in Northampton after returning to England and, when informed he was facing an 18-year sentence, made his offer to incriminate not only his fellow gang members but also every felon with whom he had been involved.
Smalls was by no means the first "grass". The Kray twins were undone a few years earlier with the help of the testimony of one of their former lieutenants. But the scale and importance of Smalls' betrayal earned him special treatment. An agreement was drawn up with Sir Norman Skelhorn, the director of public prosecutions, granting Smalls complete immunity from paying the price for his crimes.
It was the first – and only – time that a self-confessed criminal has been allowed to escape all punishment in return for turning Queen's evidence. In the wake of the agreement, the law lords ruled it had been an "unholy deal" and required that all future supergrasses should serve a prison sentence, albeit one that was significantly reduced.
The case opened the flood gates for a succession of snouts, snitches and stoolies that allowed the Yard to reverse the tide of armed robberies in the capital by the late 1980s as career criminals switched their attention to the drugs trade in search of quicker and easier profits.
It is perhaps a mark of the ruthlessness of globalised narcotics trade that the "set piece" armed robbery, as shown by the £53m Securitas raid in Kent last year, is making a return.
The success of the supergrasses also came at a price. Eventually, the system became tainted by claims that it was being manipulated to settle old scores and tales of the luxury accommodation afforded to its star witnesses.
Maurice O'Mahoney, a notoriously violent armed robber who dubbed himself "King Squealer" after passing on more than 150 names in return for a five-year jail term, became a minor celebrity in the late 1970s when it emerged he was serving his sentence in Chiswick police station with a free supply of alcohol and conjugal visits with his girlfriend.
It became standard practice for supergrass inmates to be housed in special prison wings with extra allowances before being released into a witness protection scheme complete with plastic surgery and resettlement in Australia or Canada when it was deemed appropriate.
O'Mahoney summed up the enduring price paid by the supergrasses for their betrayal. He said: "I haven't got peace of mind. How could I with the thought that some maniac might gun me down?"
But whether out of bravado, fatalism or remorse, Bertie Smalls rejected all the Yard's offers of an anonymous retirement. Within a few years, he had returned to his favourite neighbourhoods in north London and could be seen drinking in pubs, boasting of his weekly stipend from the Yard.
It was therefore a further irony that the work of the criminal justice system allowed him to survive. Bobby King, one of the robbers who was jailed on Smalls' evidence, told how he once saw his betrayer in the Crouch End area of London after his release from prison. King said he considered it a test of his reformed character that he was able to resist the urge to kill his supergrass.