Ben Foster (in-universe)

Ben Foster was a human musical conductor, who conducted the Proms at the Royal Albert Hall on 27 July 2008.

On 27 July 2008, during the Proms, a space portal opened between the Doctor's TARDIS and a point above Albert Hall's orchestra pit. Through that hole, the Tenth Doctor passed sheet music for his new composition, "Ode to the Universe", to the orchestra. He then asked the orchestra to play the song, and for Ben Foster to step down in favour of the Doctor's conduct of the orchestra himself using his sonic screwdriver. A Graske snuck through the portal, armed with the Doctor's water pistol with which he threatened Foster, the orchestra, and the audience. He was pulled back from Albert Hall, into the TARDIS, when the Doctor reversed the polarity of the neutron flow. The audience were told by the Doctor to listen to the music inside of them. (TV: Music of the Spheres)

As they kept cheering after the portal closed, the Hall was suddenly invaded by Daleks led by Davros, who had travelled back in time to transform the Hall into the imperial palace of a new Dalek Empire. To mark his victory, Davros ordered the orchestra to play Dalek music celebrating destruction, with Ben Foster facing extermination unless he complied. However, before the Daleks could stop them, the musicians began playing an ethereal music which invoked the power of the Bad Wolf entity, banishing the Daleks and Davros back through time in a red glow. (TV: The Daleks & Davros)

Behind the scenes
Ben Foster played himself in the two skits within Doctor Who at the Proms 2008.