Alfie Atherton, 18, of Saxon Lea Court, Saxon Road, E3, was sentenced to four years for robbery.
Charles Knight, 20, of Crowland Road, N15, was sentenced to eight years for robbery.
Dominic Charles, 22, of Girdlestone Walk, N19, was sentenced to seven and a half years for robbery.
Emilio Aristides, 21, of 217 Camden Road, NW1, was sentenced to seven and a half years for robbery.
All four men pleaded guilty to robbery on 21 December 2010.
On Thursday 14th October 2010, at approximately 10:40hrs, Atherton, Knight, Charles and Aristides, along with two other men, rode on three high-powered sports motorbikes to the front entrance of Ernest Jones, Kensington High Street.
All six men wore dark clothing and crash helmets with the visors down. Three of the men, who rode as pillion passengers, carried sledgehammers.
The pillion passengers got off the bikes with their weapons and two of them smashed through glass display cabinets.
They stole 26 Rolex and Longines watches (valued at approximately £155K) and stuffed them into holdalls.
Whilst the three riders lay in wait for their accomplices, they circled their bikes outside the shop, revving their engines in order to intimidate the public and stop traffic.
As the robbery was in progress, Dominic Charles stayed outside the shop, acting as a ‘look-out.’ He waved his sledgehammer around to threaten and intimidate passers-by into staying back.
At this point a member of the public moved towards Charles to intervene, causing him to drop his weapon and flee onto a bike.
Many onlookers stood back in fear and in shock, and some even recorded the events on their mobile phones; however as the robbers attempted to get back on their bikes, some passers-by attempted to apprehend the suspects.
Aristides was pulled off his bike and was successfully detained. He was subsequently arrested by officers, moments later, at the scene.
The five remaining suspects made off using two motorcycles. They split-off into different directions.
Atherton, Charles and Knight were arrested in nearby Holland Park, after abandoning their bike.
The two other suspects, who rode their silver Street Triple R bike north-bound, remain outstanding.
Detective Superintendent John O’Leary, of the MPS Flying Squad, said: “I would like to express my gratitude for the bravery of the members of the public who intervened. Their actions and those of local officers from Kensington & Chelsea have led directly to this active, criminal gang being convicted today.
“Whilst we would always urge people not to put themselves in danger, I can only applaud the actions of those who intervened whether directly or by filming events.”
Detective Inspector Jason Prins, in charge of the investigation said: “This was a violent robbery in broad daylight in one of London’s busiest shopping streets and the events must have been terrifying for the employees and members of the public who witnessed it.
“I would like to pay tribute to the onlookers who intervened – in particular those who pulled Emilio Aristides off his motorbike and detained him until the arrival of police officers. We also give thanks to those who filmed the incident on their mobile phones. This video footage became crucial evidence and contributed greatly to guilty pleas from all four defendants.
“Today’s’ sentences send out a strong message that this type of criminal behaviour will not be tolerated and that the public and the police can work together against criminals.
“There are two suspects who are outstanding and we continue to appeal to anyone with any information to contact Barnes Flying Squad on 020 8247 4804; or if you wish to remain anonymous, call Crimestoppers on 0800 555 111.”
Alfie Atherton was sentenced to an additional four years imprisonment (to run consecutively) for robbery of a cash in transit delivery van at Muswell Hill Broadway, N10 on 5 August 2010.
All 26 watches have been recovered in good condition. They will be returned to Ernest Jones in due course.