Hatton Garden jewellery heist: Police received call while thieves were inside but did nothing

An alarm system sent an automated alert to Scotland Yard in the early hours of Friday morning, while the raid was reportedly being carried out

Burglars got away with millions of pounds of gems

Police have admitted that they received a call as jewellery thieves were carrying out a multi-million pound heist inside London vaults but did nothing because a computer system decided that “no response was required”.

Sophisticated thieves got away with an estimated £200 million of diamonds and jewels from safety deposit boxes beneath the capital’s jewellery quarter over the Easter bank holiday.

Scotland Yard initially said officers were first called after workers arrived at 8am on Tuesday but today admitted that an intruder alarm set off at Hatton Garden Safety Deposit Ltd sparked an automated call days before.

The Metropolitan Police’s Central Communications Command received the alert at 20 minutes after midnight on Good Friday from the Southern Monitoring Alarm Company.

“The call stated that a confirmed intruder alarm had been activated at the Hatton Garden Safe Deposit Ltd,” a spokesperson said.

“The call was recorded and transferred to the police's CAD (computer aided despatch) system.

“A grade was applied to the call that meant that no police response was deemed to be required.

“We are now investigating why this grade was applied to the call. This investigation is being carried out locally.”

Although the spokesperson claimed it was “too early to say” if the handling of the call had an impact on the burglary, it came at a time when the thieves were believed to be inside the building.

Preliminary investigations indicate they arrived after employees left on Thursday evening and escaped at some point before police arrived on Tuesday.

A security guard had also responded to the alarm on Good Friday but did not search inside “because he doesn't get paid enough”, one client claimed he was told.

Jewels on display at the Hatton Garden Safe Deposit (EPA)

There was no sign of forced entry to the outside of the building and the gang were believed to have disabled the communal lift on the second floor and then used the shaft to climb down into the basement.

They made their way to the vault, where they used a heavy duty drill to bore holes into its reinforced, two-metre-thick, wall to access 70 safety deposit boxes, police said.

Officers who entered the vault on Tuesday described “chaotic scenes” with dust and debris covering floors strewn with discarded safety deposit boxes and numerous power tools, including an angle grinder and crowbars.

A local jeweller said that the hours of drilling would not have surprised nearby residents as many had been sent a letter informing them of works related to the Crossrail project.