Roberts was the British ambassador in Moscow at the time. A key difference in the British and American strategic opportunities is that America was the strongest nation in the world and had military muscle, while Britain could neither threaten nor oppose threats from Russia.
Here are two quotes (copied from http://thedogsbarkbutthecaravanmoveson.blogspot.ca):
"At the same time we can offer civil and political liberties which are unknown in the Soviet Union and which would be the envy of its inhabitants... There is no chance of us seizing the initiative unless we are prepared to back some political doctrine as an alternative to communism. The obvious choice is social democracy, but if we were to do this we might not commend ourselves to the Americans."
"Soviet Russia has reached a similar stage in development as revolutionary France when the First Empire had become solidly established. Although Soviet Russia intends to spread her revolution by all possible means, world revolution is no longer part of the programme."
No one has typed out the Telegram for the world of the internet. It is available at this scholo-monopolistic site for a fee: http://jch.sagepub.com/cgi/pdf_extract/25/1/103?ck=nck