Emily Blunt found it ''virtually impossible'' to shoot her first musical number for 'Mary Poppins Returns' because she was so emotional.

The 35-year-old actress - who has daughters Hazel, four, and Violet, two, with husband John Krasinski - struggled with performing the moving song as the titular character because it turned her thoughts to her own family.

She explained: ''The first few times I sang 'The Place Where Lost Things Go', I was so moved by it, I found it virtually impossible to get through it.

''It was so emotional for me because I did think of my own children and these children in the film - their sense of loss, trying to hold their father together.

''They have dealt with something so agonising and profound - to lose a parent and to be so young and miss her so much.''

Emily refused to rewatch the original 'Mary Poppins' movie before she started filming the sequel and thinks she made the right decision because she was ''floored'' when she went back to the 1964 classic - which starred Dame Julie Andrews as the magical nanny - after shooting had wrapped.

She said: ''Although I'd seen it as a child, I decided not to watch the original so close to shooting our version. I just decided to go on my gut instinct.

''As soon as we wrapped, I watched the original and was just floored by it. I was probably relieved that I hadn't watched it because I was like, 'Oh my God, she's amazing.' ''

Instead, the British star found P.L. Travers' original novels ''enormously helpful'' when it came to preparing for the part.

She told Britain's OK! magazine: ''I found the books enormously helpful.

''She leapt off the page at me, just in how complicated she is.

''She's stern, incredibly rude and vain but funny, and yet there's this humanity.

''She has such a childlike wonder and is probably a bit of an adrenaline junkie. She's so enigmatic.

''It was such a delicious character to play. Loved her.''