The Northumberland joins venues such as the QEII Conference Centre and the Royal Society of Medicine on the list.
"It is rare that a new venue as exciting as The Northumberland at Trafalgar Square is brought back to life after 70 years in the heart of London's event and hospitality portfolio," said The Westminster Collection CEO René Dee.
"It is also further evidence of the confidence being expressed in Westminster, and London's thriving business tourism business."
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