As Buffy draws to a close in America, Joss Whedon told reporters how the series had evolved over the years - often in unexpected directions.

"It's been very close to what I envisioned, except that it grew up a lot more," he revealed in a conference call last week.

"When I started the show, I didn't know its full potential, because I just had the basic notion of 'It's tough to make it in high school, and it'll be funny and evolving and scary and really hit on things that people can relate to.'"

"I didn't know how good my actors would be," Joss added. "I didn't know how long we'd go and how much they'd grow and change and how far we could go with the medium and how much the network would let us do. Or networks, I should say.

"So did I know I was going to make a musical? Or did I know even that Buffy was going to sleep with Angel, and he would go bad? No. It just kept growing."