71 security boxes were raided over easter weekend in £ 60m london heist .
in january 2013 , 294 security vaults were targeted at volksbank , berlin .
in both cases , gangs left with millions worth of diamonds , gold and silver .
both gangs used pneumatic drills on the vaults , while dressed as workmen .
police - who missed alarms during both raids - believe thefts could be ` inside jobs '