Strategy: Here's a minute-by-minute timeline of the Hatton Garden jewelry heist, Britain's biggest robbery

Although the robbers were professional, they may have left behind clues.

The Hatton Garden Safe Deposit robbery was incredibly well-planned: A gang of up to seven men may have made off with £200 million ($300 million) in gold, jewels and diamonds after abseiling down a lift shaft and drilling into the side of a concrete vault.

Over Easter weekend — a four-day holiday during which no business is conducted — the men worked with a 77-pound, £3,500 Hilti DD350 drill to cut through 2 metres of concrete. It took them two and a half days to break into the vault and rifle 72 safety deposit boxes, many of them filled with unregistered, uninsured jewelry from the local diamond trade. It's not clear how much has been stolen, but lower estimates come in at £60 million. It is likely to be the biggest robbery in UK history.

The robbers — nicknamed Mr Ginger, Mr Strong, Mr Montana, The Gent, The Tall Man, Moped Man and The Old Man by The Mirror — even drove away and, the next day, came back to finish the job. They used a white transit van and a moped in the operation.

Although the robbers were professional, they may have left behind certain clues. Most obviously, the raid began exactly four minutes after the vault was locked — suggesting they had inside knowledge. One robber exposed part of his face, and two exposed their hair colours — grey and ginger.

And, despite the fact they had plenty of time, they left behind a bunch of tools and equipment, including that signature heavy-duty drill.

We put together this timeline of exactly how the robbery went down from reports from the BBC and this video obtained by The Mirror, which shows the CCTV view of the door of the Hatton Garden vault.

December 11, 2014

Two £3,500 Hilti DD350 drills and another £63,000 of equipment are stolen from a construction site on Fetter Lane, London, according to The Mirror. Hilti only sells a few hundred units of that type of drill.

April 1 (Wednesday)

12.00: An underground fire breaks out in the nearby Holborn neighbourhood and burns for several days. The fire was fuelled by a gas leak, and lasted 36 hours, according to the BBC. There were still problems over the Bank Holiday break. The fire disables the neighborhood and ties up emergency services for days. John O'Connor, the former head of Scotland Yard's Flying Squad, tells LBC he believes it is too much of a coincidence. The Met's helicopter is used to guide firefighters.

April 2 (Thursday):

21.19: Staff at Hatton Garden lock the doors for the weekend.

21.23 Mr Ginger appears and descends to the vault. A few minutes later three men get out of a white van and follow him with wheelie bins. A man arrives and makes his way downstairs towards the vault. Mr Ginger is wearing latex gloves, a blue jacket, and a black flat cap. He is carrying a black sack.

Mr Montana and Mr Strong drag in more wheelie bins.

April 3 (Good Friday)

00:21: Police at Scotland Yard are informed that the burglar alarm has been triggered. They do not respond.

01.00 (roughly): Mr Ginger is seen above ground briefly.

07.51: The gang is seen above ground for the first time since the night before. They are bringing up their equipment in stages. It includes a red wrench, bolt cutters, two red tool boxes, a big black bucket, an angle grinder and crowbars.

08:05: First appearance of The Old Man. He has grey hair. Three gang members talk. One is wearing pink trainers.

8.12: The transit van returns and the gang load it up.

10.00: The Holborn fire is finally brought under control.

April 4 (Easter Saturday)

22.17: Mr Ginger returns more than 18 hours after the gang's first shift in the vault. He is wearing latex gloves and carrying a black sack. He goes downstairs towards the vault. He is later joined by two other men over an hour later.

22.32: The Tall Man appears wearing a flat cap and carrying a blue Nike bag and a red tool box. Only three men appear to have returned to the scene.

April 5 (Easter Sunday)

05.46: The gang begin bringing up more stuff to the surface.

06.01: According to The Mirror, The Old Man makes a mistake as he rests while dragging a bin: "The Old Man leans on the bin, struggling for breath, as he reveals a clear shot of the side of his face."

April 6 (Easter Monday)

Nothing happens.

April 7 (Tuesday)

08.10: Met Flying Squad called to the scene, according to the BBC.

Detective Chief Inspector Paul Johnson of the Flying Squad gives a briefing on what happened inside the vault:

• The communal lift on the second floor was disabled.
• They climbed down the lift shaft into the basement
• They forced open a set of shutter doors before making their way to the vault.
• At the vault, the gang used a Hilti DD 350 drill to cut into the vault.
• The vault is 2 metres thick, made of concrete.
• The gang left behind numerous power tools.
• The vault is left in disarray, covered in debris and empty deposit boxes.
• There was no sign of forced entry from the outside of the building.

April 11: The BBC reports that police have yet to interview the owner of the building, who is overseas.

April 13: The Holborn fire was not deliberately set, according to London fire commissioner Ron Dobson.

Although the robbers were professional, they may have left behind clues. Read Full Story