How did Chips Channon know two days in advance that Germany would invade Russia on 22 June 1941?

I learnt some interesting things last night from reading a review of the second volume of the (almost) unexpurgated diaries of Anglo-American diarist and Conservative MP Chips Channon.

Channon, who wasn't in the government (he was merely Rab Butler's P.P.S., i.e. bag carrier), told the people he dined with on 20 June 1941 that Germany would invade Russia two days later, which is what happened.

How did he know and Stalin not?

He assumed, as most people did, that Germany would easily defeat the Bolsheviks and became frightened that this would mean the end of the British empire and the British upper class. Neither would have been the case. In fact, Japan attacking Britain and the victory of America and the USSR helped achieve this, in about twenty years.

He chose to leave America to go to Oxford and live in England because he saw American culture as a threat to European civilisation. There might be something in that.

On the other hand he thought the Nazis would save Western civilisation and was heartbroken when Germany annexed Czechia and he realised they wouldn't.

I also didn't know the Countess of Avon, Anthony Eden's widow, is still alive aged 101. I remember him dying in Jamaica at a great age when I was in the fourth year at school with O Levels still almost a year and a half away.