Langham-sponsored history directly identifies Lady Gaga as a guest of The Langham London, and The Caterer contemporaneously confirms her stay during the June 2015 Tony Bennett concerts; Guardian and Capital reporting provides earlier exact-property context from 2013.
Lady Gaga stayed at The Langham London during her June 2015 concerts with Tony Bennett at the Royal Albert Hall. The relationship is confirmed by Langham-sponsored history and by contemporaneous British hospitality reporting that separates her accommodation from a birthday event at the property.
Source conclusion:
The cited sources support a stay at the named hotel.
