The 77-year-old TV presenter has enjoyed a lengthy friendship with Sir Cliff, and she is saddened to see how the three-year police probe into historic sex offences, which proved to be false, has affected his zest for life.
In an extract from her new autobiography, 'My Life', Gloria explained: ''I felt utter disbelief when, in 2014, his Berkshire home was raided by police - with the BBC hovering in a helicopter to cover the shock event.
''Operation Yewtree had been set up to deal with historic sex abuse allegations after the Jimmy Savile scandal and Cliff had been accused of assaulting a boy of 15 at a Christian rally, three decades previously.
''I never believed the allegations for a second. I rang Cliff and said: 'Sit down and don't say anything. This is what you have to do. This is the best lawyer for you.'
''I was with him from the very beginning. Sitting in Portugal, watching his apartment being raided, Cliff fell to his knees and wept. A friend with him said 'get up. You know you've done nothing wrong' but that was only the start of a nightmare.''
The 76-year-old star was cleared of the allegations in 2016, but Gloria admitted he has still not fully recovered from the stressful ordeal.
She shared: ''He was in a state of total shock. He had no idea who his accuser was and there was little information from the police. He was appalled that anybody would put him through such agony.
''And so began nearly three years of torture. Friends kept going to Portugal to see him but he was effectively imprisoned there.
''Finally, in June 2016, the CPS said there was not enough evidence and no further action would be taken, while the police and the BBC were both heavily criticised for their conduct.
''But Cliff was understandably tormented because he felt the CPS had left him open to 'no smoke without fire' insinuations. 'How can there be any evidence for something that never took place?'
''Even now he cannot believe what's happened - it literally eats away at him. He lost so much weight that when he hugged you, it felt like skin and bone.
''Cliff lost his joy for life. We were constantly on the phone and he went over and over the details because it was tormenting him.
''The impact on him has been so severe and I don't think he'll ever fully get over it.''
His new album Underneath It All is out now.