LONDON: Music producer Mark Ronson says he will never work with singer Lily Allen again due to creative differences. 'I can't go back to working with Lily. There's been no falling out but our creative relationship has ended,' thesun.co.uk quoted the producer as saying. Ronson shot to fame after working with Allen in 2006 for the album 'Alright, Still'. However, he is keen to reunite with Amy Winehouse as he is proud of his work on her 'Back To Black' album.