Firefighters were called to the Grapes, Limehouse, east London, to put out the fire at the pub, which is co-owned by McKellen; theatre and film director Sean Mathias; and Evgeny Lebedev, publisher of the Evening Standard newspaper.
There was smoke and fire damage to the second floor. A woman also suffered from smoke inhalation and was taken to hospital by London Ambulance Service crews.
A London Fire Brigade spokesperson said: “Some electrical appliances use more power than others, so be mindful of not overloading your extension leads.
“Power-hungry appliances such as kettles, toasters and microwaves shouldn't be on the same extension.
“It's also important to fully unwind drum extensions leads. If you leave them coiled, they can overheat and cause a fire.”
A common cause
When firefighters arrived, the crews damped down the area to make sure the fire was fully extinguished.
The firefighters have since issued a safety warning and shared details of how to avoid overloading extension leads on their Twitter page.
The spokesperson continued: “Overloaded sockets are one of the most common causes of electrical fires.”
The pub’s history
For 500 years, the historic pub has settled on the Limehouse Reach and has even survived the bombings in World War II – it stands as one of the oldest pubs in London.
The Grapes is a Grade II-listed public house and situated not far from the bustle of Canary Wharf.
Charles Dickens was a patron, and even referred to the pub in his novel Our Mutual Friend.