The Serious Organised Crime Agency needs another two years to prove it merits its lead role in tackling the £40bn black economy, according to the woman in charge of prosecuting the country’s most powerful criminal gangs.

With a £430m yearly budget, the three-year-old Soca has been criticised for not seizing more assets from the estimated 4,000 gangs operating in the UK, leading to speculation about its fate under a Conservative government.