The thespian, 80, made a blink or you'll miss it appearance in a recent Les Miserables performance in Newcastle.
Famed thespian Sir Ian McKellen showed off his singing skills with the cast of Les Miserables.
However, the singalong did not take place on the stage but in a Newcastle pub late on Friday (August 16).
Earlier in the evening, the actor had surprised the audience at the Newcastle's Theatre Royal with a blink or you'll miss it appearance on the barricade as a character called 'Hugo Victor' — a tribute to French author Victor Hugo who penned the novel the musical is based on.
Cast member Will Richardson, who posted the impromptu pub performance of "One More Day" on social media, described McKellen as "such a gentleman and so very kind."
"He said he's desperate to be in it [Les Miserables musical]...so we let him sing with us," he added.
The classically-trained actor was in Newcastle to perform his one-man show as part of a theatre tour to celebrate his 80th birthday in which he recreates his most iconic roles from Gandalf to Macbeth.