Paula Abdul poses for photographers backstage during the 9th season finale of 'American Idol' in Los Angeles May 26, 2010.
Paula Abdul poses for photographers backstage during the 9th season finale of 'American Idol' in Los Angeles May 26, 2010. Reuters/Mario Anzuoni

One of the worst guest stars that “Studio 10” never actually had was a “pint-sized Australian singer,” the show’s exec producer has revealed. The best ones include Paula Abdul, “The Bold and the Beautiful” star Katherine Kelly Lang and a classic “Doctor Who” star.

Exec producer Rob McKnight has shared a few of the best and worst guest stars that the mid-morning talk show has ever had since it launched in November 2013. The show is celebrating its 1000th episode Thursday.

For McKnight, the best guest was Abdul, he told news.com.au. The multi-hyphenate American-Canadian volunteered to appear on the show, and she was far from being a diva that other reports claimed her to be.

Abdul was shooting “So You Think You Can Dance Australia” in 2014 when she apparently saw an episode of the Network Ten breakfast show. She personally called McKnight to offer her services.

“She came on once a week for the eight weeks she was out here shooting and she was fantastic,” he told the publication. “She was up for anything and couldn’t have been a nicer person behind the scenes. She was not a tantrum-throwing diva.”

Lang, who is best known for her role as Brooke Logan on the American daytime soap “The Bold and the Beautiful,” was the most generous with their time among all her co-stars. McKnight said Lang has always been a good sport whenever the show does their B&B skits, But McKnight was most impressed when they did a challenge and had to pour a pancake mixture over Lang’s head.

“Can you think of many Hollywood stars that would allow you to poor that over their head? I can’t think of too many,” he said.

Peter Davison, who played the fifth incarnation of the titular character in “Doctor Who,” was McKnight’s third favourite guest, even though the episode turned out to be terrible. As a Whovian, the producer said it was his “personal indulgence” to have Davison on the show.

“I never should have done it; it’s terrible, it’s pathetic, but I will say it was our highest rating episode that year so I always refer to it as the ‘McKnight spike.’”

Television presenter Patti Newton and Opposition Leader Bill Shorten also made McKnight’s honourable mention list. Shorten, McKnight said, did not give them a list of what he was willing to talk about.

The worst ‘Studio 10’ guests

The exec prod wouldn’t give names, but he gave clues. According to him, the worst ever guest was a “camp English comedian” who tried to take over the show when he failed to understand the format.

The second one is another comedian, this time an Australian, who wasn’t funny. The comedian was trying hard to be funny but the studio audience were not reacting positively to him. He ended up shouting at them, “What’s wrong with you? This is funny!”

The third worst guest of all time had not really appeared on the show. However, this “pint-sized Australian singer” made the list because not only did that guest cancel on them at the last minute, the guest also went to a competitor’s show.

McKnight explained that he had a heated phone call with the singer’s management so he warned them that they would never have that guest on the show if they cancelled that guest’s appearance.

“Their management laughed in our face and they went on the competitor’s show and I can honestly say 1,000 episodes in that we have never had that person on our show and we never will, despite their management approaching us many, many times to have them on,” he said. “We’re a show of our word.”

“Studio 10” is presented by Ita Buttrose, Joe Hildebrand, Sarah Harris, Jessica Rowe and Denise Dysdale. It first aired in 2013 as Network Ten’s replacement for previously cancelled “The Circle.”