Privy Council minutes from Tuesday have now been published regarding Peter Mandelson.
“An Order striking out The Lord Mandelson from the List of Members of His Majesty’s Most Honourable Privy Council.”
The Order in Council stripping Mandelson of his peerage has also been published:

Mandelson is no longer the Right Honourable…
The government is briefing that legislation to strip Mandelson of his peerage won’t come until after the King’s Speech in May. No10 says this is because it is putting together wider legislation to remove peers in general. A manufactured delay…
Lord Khan in the Telegraph: “I hope, and I say this in a non-pompous way, that the public service I do will bring rewards in this world and the hereafter,” he says. “I’m hoping the work I do is earning me Brownie points.”