Moped-riding robbers who carried out more than 103 crimes on victims including former chancellor George Osborne have been locked up for more than 13 years.
The gang operated in the London boroughs of Camden, Westminster, Islington, and Kensington and Chelsea over five days, and involved three teenagers and a fourth unknown robber, who was armed with a hammer, on mopeds, Southwark Crown Court was told.
Mr Osborne was among the victims when an attempt was made to snatch his mobile phone outside the BBC.
Judge David Tomlinson, sitting at London's Southwark Crown Court, said: "What happened here was prolific moped-enabled crimes involving a series of robberies and attempted robberies on five separate dates over a period of two and a half weeks, riding around on mopeds primarily targeting pedestrians who were holding their mobile phones in their hands."
Claude Parkinson, 18, of Islington, north London, and two others aged 16 and 15 who cannot be named because of their age, chatted and joked with each other in the dock as they were sentenced.
All three had previously pleaded guilty to conspiracy to commit robbery.
Another man, Shamsul Chowdhury, 40, of Tower Hamlets, east London, was sentenced to four years and 10 months after pleading guilty to handling stolen goods.
Parkinson was sentenced to five years and three months while the teenagers were each sentenced to four years and two months.
In 18 days between April 18 and May 5 this year, there were 212 moped robbery and snatch offences in Westminster alone, of which 83 were committed by the gang.
The judge said: "By May 4 2017 you had resorted to the use of weapons to enforce your intentions.
"With or without weapons, throughout this course of conduct there was a risk to the safety and wellbeing of members of our community.
"By May 4 your willingness to use weapons to threaten violence showed that your offending had spiralled out of control."