Detective Superintendent Stephen Ratcliffe said this was "a gang of experienced criminals who had been the subject of an investigation by the special projects team at the Metropolitan Police for a couple of months before this robbery."
More top news
City Hall has warned that Londoners should avoid coming to the centre of the capital on New Year's Eve unless you have a ticket.
Members of the Queen's Guard have been assigned the protection of armed police, amid reports they could be targeted by terrorists.
When Robin Ollington wrote to Buckingham Palace suggesting they introduce a Christmas tree, he didn't expect them to write back...