Benedict Cumberbatch made a surprise career reinvention as a rock star this week, joining David Gilmour on stage in London to help sing a classic by Gilmour’s old band Pink Floyd, ‘Comfortably Numb’.

Guitarist Gilmour was playing the third gig in a five-night residency at London’s Royal Albert Hall on Wednesday night (September 28th), when the Marvel actor walked out onstage for the 1979 song, taken from Floyd’s classic album The Wall.

The track was, of course, originally sung by Gilmour’s old bandmate Roger Waters, who acrimoniously left Pink Floyd in 1985. Gilmour has continued to perform the song live since, but frequently uses guest vocalists for Waters’ part – including the late David Bowie, who joined him onstage in exactly the same venue 10 years ago.

In an extremely rare reunion, Gilmour actually joined Waters onstage in 2011 during the latter’s show at London’s O2 Arena.

More: Benedict Cumberbatch interviews Tom Hiddleston, but avoids the Taylor Swift question

The series of gigs finish the promotional tour for Gilmour’s recent studio album Rattle That Lock, which was released in 2015. “Who knew he could sing?” Gilmour asked the audience after the song had finished.

However, keen fans will know that 40 year old Cumberbatch, whose Marvel debut comes in November with the release of Doctor Strange, has previously sung in his movies before, notably in 2013’s August: Osage County with a rendition of ‘Can’t Keep It Inside’.

He is also known to be a keen music fan, regularly attending gigs in London when not busy with his hectic filming schedule.

The fourth series of ‘Sherlock’, the series that launched Cumberbatch to international fame, has now finished. The first episode of the new season is due to be broadcast on New Year’s Day 2017, with Toby Jones playing a villain in the following episode ‘The Lying Detective’.

More: ‘Sherlock’ convention attendees refused refund despite Benedict Cumberbatch cancelling appearance