The catch is that the offer only applies to a small number of people.
Similar to Nando’s black card, which offers diners free meals, Dishoom’s secret keyring is given to a few lucky people who will then be given the chance to have their meal on the house.
The Matka keyring, as it’s called, is named after the Hindi word for pot or cup. Matka is also a slang term for the underground lottery that originated in Bombay in 1962.
Those who have a keyring are permitted to discreetly show it to a member of staff when asking for the bill.
The staff member will then return with a dice, and if a six is rolled, the group’s entire meal will be free.
“For a select number of our friends, we let our little Matka keyring decide who picks up your bill – you, or us,” Dishoom explains.
“Attach your Dishoom token to a key-chain. You may now use it to invoke special privileges.
“If you roll a six, your meal is on us. Your whole table. The whole bill. Yes, we are quite serious.
“On weekdays, request your bill before 6pm and present your token, you will then get a roll of our Matka dice.”
As for how to get your hands on a Matka keyring, Dishoom says that anyone can ask for one.
A Dishoom representative said: “There are several designs of Matka available, inspired by the unique stories of each restaurant.
“For example, the Dishoom Carnaby Matka is a plectrum, inspired by the Bombay-London music scene of the 1960s.
“Dishoom Covent Garden has the initials ND engraved on a copper coin, representing the “New Dishoom” on this site, where Dishoom originated in 2010.”
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