Beadle, 59, recently battled leukemia after falling ill in 2005, less than a year after he had a kidney tumor removed.
The former host of "You've Been Framed" was admitted to a hospital near his North London home a few days ago to be treated for pneumonia, the Daily Mail reported Friday.
"Anybody suffering from pneumonia is going to be pretty poorly," Beadle's agent Michael Cohen told the newspaper. "We are all hopeful he will pull through and be fine."
Beadle's wife, Sue, and daughters Cassie, 21, and Bonnie, 19, were by his side Thursday, the report said.