LONDON -- It was the persistent rumors of the dossier that had Sir Andrew Wood most concerned; Explosive material that could allow the Russians to blackmail the president-elect.

“Anybody has reason to be concerned if they think the future president of the United States is somehow under Russian or any other tutelage,” Wood said.

The retired British ambassador to Russia was concerned enough that he met with Sen. John McCain at a security conference last November.

Sir Andrew Wood CBS News

“It seemed to me that it was right, knowing that I had the chance to see, speak to the senator, that it was only right for me to say, ‘this does exist,’” Wood said to CBS News correspondent Charlie D’Agata.

The dossier contains unverified allegations of President-elect Donald Trump’s sexual behavior and potential bribes.

Trump says it’s a complete fabrication.

The report was compiled by former British spy Christopher Steele.

Christopher Steele is seen in a photo obtained by CBS News.

“You know him, what kind of man is he?” D’Agata asked.

“He’s an honest professional. And nobody in his position would wish to make this sort of stuff up because, after all, it’s a potentially dangerous problem,” Wood replied.

Steele has fled his home southwest of London and has gone into hiding.

Wood said he doesn’t know if the allegations are true, but the tactic of sexual entrapment by Russia’s intelligence services, the FSB, is widespread.

“It is just a very common practice and for the FSB to say they never use it is laughable,” he said.

In 2013, Trump returned to Moscow for the Miss Universe pageant, and used the occasion to try and develop other business ties.

“No one I suppose knew that he was going to become president then. But why not give it a go and stick it away for possible use later?” Wood said.

“Because that’s what Russians do?” D’Agata asked.

“Yes,” Wood replied.