One of the men was caught when City workers and police grabbed him after a raid in Liverpool Street
Three robbers have admitted carrying out a series of raids on jewellers and money transfer shops in London and Manchester.
The men smashed their way into the stores wielding sledgehammers and machetes before escaping on mopeds.
Over the course of a year they struck at seven stores in London and Manchester.
It is estimated they stole cash, watches and jewellery worth £500,000 in total.
Disguised in helmets and gloves, they used concrete blocks and hammers to shatter window displays and glass cabinets and threaten staff with knives and machetes before making off on stolen scooters or mopeds.
Thomas O'Connor, 23, of Swan Road, Surrey Quays, Alex Parle, 22, of Brunel Road, Surrey Quays, and Conor Gartland, 18, from Druid Street in Bankside, pleaded guilty at the Old Bailey to conspiracy to commit robbery.
The raiders used concrete blocks to break into Carr Jewellers in Liverpool Street in January
One of the robbers was caught when City workers and a plain-clothes police officer blocked his escape after a robbery which was captured in mobile phone footage by a passer-by.
Where the gang struck
22 January 2014: Alex Parle, Conor Gartland and Thomas O'Connor snatched jewellery and Rolex watches from Carr Jewellers in London's Liverpool Street.
16 February 2014: Gartland and an unknown person were accused of trying to rob Akdeniz Jewellers, in Walworth Road, south east London.
20 December 2014: All three defendants took £1,250 from Bilex International in Peckham High Street.
20 December 2014: Later the same day, Parle and Gartland made off with £2,392.47 from Unistream Money Transfer Shop in West Ham Lane, Stratford, east London.
22 December 2014: Parle, Gartland and O'Connor stole £29,000 from Kushiaria Money Exchange, in Commercial Road, Tower Hamlets, east London
13 January 2016: All three defendants took £37,448.77 of jewellery and watches from a jeweller's in Crofton Road, Orpington, Kent.
15 January 2015: The gang took eight watches during a raid on the Cheshire Watch Company in King Street West, Manchester.
