I THOUGHT I had seen the last of Frank Sinatra that July evening of 1990 when he came to Ibrox Stadium to put the ultimate touch of melodic class to Glasgow's Year as European City of Culture.

''He's finished!'' they said in advance. But he wasn't.

Under a low cloud of drizzle, he took a radio microphone and walked round the track, well away from his orchestra, and gave us the finest rendering of Strangers in the Night I had ever heard. We waved him goodbye and knew that, at the age of 75, that was likely to be that.

A few years later however, I was driving into Las Vegas when the billboards on the strip were telling me what I could hardly believe: Sinatra at the Desert Inn. Thanks entirely to a booking lady whose mother came from Aberdeen, I secured a table right in front of the stage on his last night in Vegas.

Rumours of his encroaching senility were rife; so what would it be like tonight? The curtain opened on an orchestra which started with 56 violins and spread in similar proportion.

Frank Sinatra junior was conducting and soon we were greeting the man himself, the boy from Hoboken, just across the Hudson River from Manhattan, who idolised Bing Crosby and went on to become the greatest single entertainer the world has ever known.

He belted out songs like Mack the Knife with his usual force but in the softer melodies the notes were barely there . That was understandable. But what troubled me, as I caught his eye from just a few feet away, was the touch of bewilderment, the inescapable fact that clarity had gone.

He was faltering over the names of those composers who had been his friends, Irving Berlin, Richard Rodgers, Cole Porter, Jerome Kern, George Gershwin. He even fluffed a line of My Way, though he did manage to sing: And now the end is near - and so I face the final curtain.

And we rose to give him what was perhaps the greatest ovation of his career. Suddenly the poignancy of the occasion had dawned upon us. We had been privileged on this historic night to witness the very end of Sinatra's career. He did make one other appearance on a stage but collapsed before the end.

So we stood and called out his name and he gazed back at us like a lost child. The events of this remarkable career were reeling in my head like a flickering picture show: his days with the Harry James and Tommy Dorsey orchestras; that dip in his fortunes when he flopped at the Glasgow Empire; the revival when he gained an Oscar for the 1953 film From Here To Eternity; the eventual rise to legendary status; and the four wives, including Ava Gardner.

Of course he had had moments when good judgment deserted him. Who would have believed that, without this slight figure of a man, John F Kennedy would never have seen the White House? The crooked Joseph Kennedy had persuaded Sinatra to back his son, by ensuring that the crucial state of West Virginia was ''fixed'' by the Mafia.

But all that was now lost in history. It was the voice which would be best remembered and where better to bid him goodbye than here on the Strip at Las Vegas, where he had reigned as king since that extraordinary town was created after the war.

As he made his way aimlessly off stage, the orchestra struck up once again the refrain of My Way. That was how he had done it. And as we followed his image into the wings, we knew that his voice would live forever.