'Lord Privy Seal' is actually an abbreviation for the 'Lord Keeper of the Privy Seal', i.e., the person who (nominally) looks after the seal used to authenticate personal documents 'signed' by the monarch before written signatures came into use. The post of Lord Keeper of the Privy Seal is now usually given to the governing party's leader in the House of Lords, and the monarch's personal seals (which no longer serve any official purpose) are held by the Lord Chamberlain, who is part of the Royal Household and not the Government.

My comment is a quote, from Angus Calder's book "the peoples war" -he took it from a comment made by a labour minister of the time.

For a great pun on the by name/by value: https://news.ycombinator.com/item?id=38858443

I like letter-slash-letter abbreviations but I've never run into c/f before. What does it mean? Do you remember where you first picked it up?

It's a misuse. CF no slash "compare" in backpieces, references &c. C/F appears to mean something in pre spreadsheet accounting but I did not study accounting at uni, so where I got the idea it needs a slash is beyond me.