'The first time I saw the movie I was in a state of shock' - James Lapine
'The first time I saw the movie I was in a state of shock' - James Lapine
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Are you proud of the film of Into the Woods?
Absolutely. I've never done a big studio movie before and it's been really thrilling. And it's done really well which makes it even more thrilling. It's nice to be old and still be able to have new experiences!

What sort of feedback have you had from fans of the stage show?
I wondered if some of the purists would be upset by the changes, but people seem to be pretty pleased - and theatre people aren't easy to please! Some have even liked the movie better than the show, which is a slightly odd compliment. That being said I don't read many blogs; I'm sure there's some discontent somewhere.

Was seeing the movie for the first time similar to seeing the show for the first time?
Not really. The first time I saw the movie I was somewhat in a state of shock. As the writer you tend to sit there analysing every word, it's hard just to sit back and enjoy it. I saw it before it was finished, and didn't have a 'real' experience of watching it until the premiere.

The DVD version includes a song that was cut from the movie - tell us more
It was a song for The Witch. Meryl [Streep] sings it just after Rapunzel has left her. It was a good idea for a song, it just stopped the action too much in the film, which is a half hour shorter than the stage version. It was generally felt that, as beautiful as it was, it didn't keep the trajectory of the storytelling going. But it's very beautiful to watch in and of itself on the DVD.

How has your relationship with Stephen Sondheim evolved through this project?
Rob [Marshall - director] and I didn't bring Steve into the mix until we'd finished the first draft. He was then able to come in with a fresh set of eyes and give us some really helpful feedback. It was a very collaborative process. Steve and I get along great, I don't know how else to put it. We've been working together 35 years and we're great friends as well as collaborators.

You never fall out?
Everything I do with him is a pleasure - it would be so much more interesting if I could say we fight like cats and dogs and never agree on anything, but we don't! When we do have disagreements Steve always says it's clear who cares most, and that's how we decide who wins the point. It's served us very well and I've adopted that approach elsewhere in my life, even with my wife! It's about taking your ego out of decisions.

Sondheim recently referred to Lady Gaga's Oscars performance as a 'travesty' - do you agree with that?
On that I don't agree with him! I have a pop sensibility and I like pop music. I thought Lady Gaga was great at the Oscars. I come from a very different point of view on that than Steve does. But then these things often get taken out of context - I'm sure when he says 'travesty' he's got his tongue in his cheek.

Do you think you might do more film musicals?
We've been approached about doing a movie version of Sunday in the Park with George, which really interests me and is something I think could be really fantastic, so we might do that. I'm generally really interested in film; I'm working on a film now that has no music in it at all. I also have another musical I've been sketching out the book for, though that one isn't with Steve. I'm always fiddling with several projects at once.

Into the Woods is out now on Blu-ray and DVD