Johannes Brahms
From Tardis Wiki, the free Doctor Who reference
Brahms was a composer credited for the sonata Op. 78 in G major. His composition was part of the programme for Dr Joachim and Mr Leonard Borwick's chamber concert due to take place at St James' Hall on the evening of Friday 1 July at 8.30. An advert for the concert appeared in an 1890s copy of The Times. (TV: Deep Breath)
Behind the scenes
Although his first name is not given in the episode, this is Johannes Brahms.
