Life Lin-Manuel Miranda is ready to show off his London ‘Mary Poppins’ accent: Will it fly? November 30, 2018December 1, 2018 Bryan Alexander, USA TODAY Comments Off on Lin-Manuel Miranda is ready to show off his London ‘Mary Poppins’ accent: Will it fly? Dick Van Dyke's "Mary Poppins" Cockney accent has lived in infamy. Fellow American Lin-Manuel Miranda steps up next in "Mary Poppins Returns."