The Metropolitan Police were called shortly before 2am on Monday, March, 25 and have now confirmed an investigation has been launched following the burglary.
In a statement the Met said: “Forensic examination work is continuing at the scene. No arrests have been made. Enquiries are ongoing to establish the circumstances and identify those responsible. We are not providing further information at present, and we are not disclosing details of what was stolen.”
The Sun reported that the thieves had dug a tunnel to get inside the building but police have not confirmed this.
Any witnesses, or anyone with information, should call police via 101 quoting CAD 451/mar25. To remain anonymous, call Crimestoppers on 0800 555 111.
The theft took place close to Hatton Garden, where the £14m Hatton Garden safe deposit box heist was committed in 2015.
George Attenborough & Son declined to comment.