Matthew chuckles at the schoolboy who claims to have invented the quotation "The past is another country." This is actually a common misquotation of the opening line of L.P. Hartley's 1953 novel 'The Go-Between': "The past is a foreign country: they do things differently there."
Here future Doctor Who actor Paul McGann plays a character impersonating a doctor. In 2017 Jodie Whittaker, who at the time was also a future Doctor Who actor, would play a character impersonating a doctor in Trust Me (2017).