Patti

Madame Patti was to perform her last concert of the Summer season at the Royal Albert Hall on the afternoon of Saturday 16 July. An advert for the concert appeared in a copy of The Times. (TV: Deep Breath)

Behind the scenes
Although her first name is not given in the episode, the "Madame Patti" mentioned in the advert is most likely Adelina Patti; a 19th century opera singer.