Detectives are on the trail of a "lone wolf" burglar who executed a 19-minute heist at a mansion on London’s exclusive billionaire’s row, stealing bespoke jewellery and luxury items valued at over £10 million.

The intruder gained access through a second-floor window of the 13-bedroom property on Avenue Road, St John’s Wood, on Saturday, December 7. Inside, he cracked a safe and looted other valuables, making this one of the largest residential thefts in British history.

Security footage captured the man entering at 5:11pm. He spent five minutes searching rooms on the second floor before descending to the first floor, where he located the high-value items. The burglar fled through the same window at 5:30pm.

Hermès watch

Among the stolen items were £150,000 worth of Hermès Crocodile Kelly handbags, £15,000 in cash, and £10.4 million worth of bespoke jewellery, including a Graff 10.73-carat diamond ring, De Beers butterfly diamond rings, a Hermès 3.03-carat ring, and an aquamarine ring and "Niloticus Lumière" necklace. The haul also included pink sapphire earrings from Katherine Wang shaped like butterflies, as per the police.

Van Cleef & Arpels necklace

The suspect, a white man in his late 20s or 30s with a medium build, wore a dark hoodie, cargo pants, and a grey baseball cap. Security cameras recorded him carrying a weapon, possibly a flamethrower or noxious spray, which he appeared ready to use if confronted. At one point, he narrowly avoided encountering a maid.

About eight people, including family members and staff, were inside the five-storey, 22,000 sq ft (2,045 sq metre) mansion during the break-in. The family, originally from Hong Kong, is offering rewards of up to £500,000 for information leading to the thief’s capture and conviction, as well as 10% of the value of any recovered items.

Police and private investigators are working to identify the burglar, whose face was covered. Authorities have warned that the stolen jewellery is highly distinctive and easily identifiable, urging the public and potential buyers to report any sightings or offers of sale.

DC Paulo Roberts, leading the investigation, described the crime as “brazen” and a violation of the victims’ sanctuary. “This is a brazen offence, where the suspect has entered the property while armed with an unknown weapon and violated the sanctuary of the victims’ home.

“The suspect has stolen £10.4m worth of jewellery, much of which is sentimental and unique in its design, and therefore easily identifiable.

“We urge anyone who was in the area of Avenue Road, NW8, and saw anything suspicious to please come forward. Also, if you have seen this jewellery since, someone has offered to sell you it, or you have any further information, then please also contact the police or Crimestoppers anonymously.”

Csaba Virag, the family’s chief of staff, stated the thief’s actions suggested prior experience, though fencing the items might require a larger network.

Avenue Road, known as one of the UK’s most affluent addresses, has seen a rise in high-end jewellery thefts, with claims increasing by over 40%, according to insurer Aviva.