David Bowie's photographer for his famous 1983 world tour will complete a picture book the pair had worked on together.

Denis O'Regan took more than 20,000 photos over a nine-month period on the Serious Moonlight tour, capturing the late singer on stage and off.

He and Bowie decided which images to keep for future projects together.

"He loved informal photographs," O'Regan told ITV News.

"His dressing room was open, I could walk in and out.

"We travelled together all the time, we were in the same hotel and had dinner a lot.

"So he actively wanted me to capture him, rather than keep my distance."

Both had selected images, most unseen before, that would go into a future book about the tour.

But the singer's shock death in January 2016 means O'Regan, with the approval of Bowie's family, has finished the project himself.

Two years on, O'Regan still struggles to believe the rocker is gone.

"It's very difficult going through the pictures sometimes, because he was so happy at the time," he said.

"It's a bit like someone that you knew really, really well, and that someone suddenly showed you a photo album of you together."

The book is set to go on sale later this year.