The diminutive star died on Thursday aged 85 as British officials were reportedly considering honouring him with a knighthood.
It is understood a panel that bestows the titles had received letters from famous names in support of his nomination, and if approved the actor and comedian could have become Sir Ronnie in the Queen of England’s 90th birthday honours.
Tarbuck, 76, fought back tears as he toldhe was aware of Corbett’s illness.
Asked if he knew he had motor neurone disease, Tarbuck said: “Yes I did know he wasn’t very well, and I knew exactly... sorry I’m getting a bit choked... what he had.
“And he didn’t want to see you. He said ‘I don’t want to see you like this’, but I’d speak to him on the phone. And when you did anything with him or for him, you always got a letter from him, that’s how correct he was.
“But yes I did know, unfortunately, that he wasn’t very well.”
Writing in the, a friend of the entertainer, Michael Thornton, said he contacted the UK’s Cabinet Office to propose a knighthood “several months ago”.
He said there was a “virtual stampede on the part of celebrated figures” when it came to gathering letters in support of the nomination.
At the time Corbett was “fighting to survive” after being diagnosed with suspected amyotrophic lateral sclerosis — a form of motor neurone disease, Mr Thornton said.
According to the, a low-key campaign led by comedian David Walliams to include Corbett on the honours list was launched amid concerns over his deteriorating health.
Corbett was made a CBE (Commander of the British Empire) in 2012 but the knighthood eluded him.