For a man who has dedicated so much of his acting career to the destruction of a ring, it comes as no surprise that Sir Ian McKellen would want a dab of magic to protect his personal property.

And in the shire of Tower Hamlets, the Lord of the Rings actor, whose ‘castle’ is located in Limehouse, found just that when he signed up to the new Met Trace project which helps ward off burglars.

The SmartWater kits – which contain an invisible property-marking solution, allowing owners to mark their possessions with a unique forensic code – have proven to reduce burglary by almost half across the five boroughs where it has so far been trialled.

Making reference to his recent role as Sherlock in the film Mr Holmes, Sir Ian said: “Help the police. Help yourself. Thwart the burglar. Use SmartWater. Elementary.”

Specially trained officers have been delivering the kits, which also contain warning stickers for residents to display to deter burglars.

The unique forensic code can also be used by the police to trace the items should they be stolen, and to link suspects to crime scenes.

Det Insp Chris Soole, who launched the scheme in the East End, said: “Met Trace aims to reduce burglary, deter criminals and reassure residents that we are committed to making our borough a safer place in which to live, work and visit.”

A total of 400 kits have so far been delivered to households in the East End, with thousands more planned over the next three months.

The Met has planned which addresses will be visited for the next 12 months, following three years of detailed analysis.