Sesame Street used to be the gritty setting for America's longest children's TV show.

In the new TV series the neighbourhood seems to have gone upmarket. HBO, the network behind Game of Thrones and The Wire, has taken over Sesame Street.

But the programme's makers says the changes were already in place before the new ownership deal.

North America correspondent Nick Bryant asks Elmo why in an interview for Radio 4's Today programme.

Listen to the full version of this interview