On December 12 the Mary Poppins Returns promotional tour landed in the United Kingdom with its European Premiere in London.

Public Appearances > 2018 > 12 December – ‘Mary Poppins Returns’ European Premiere in London
Public Appearances > 2018 > 12 December – ‘Mary Poppins Returns’ European Premiere after party

On Walt Disney Studios Facebook page there’s the official video of the premiere, you can watch Lin-Manuel interview at 27.00.
[EDIT] Added a link to Youtube for the premiere and an official shorter video from Disney UK.

On the red carpet Miranda gave some interviews, watch them under the cut.