"Old Estonians"

From an article in yesterday's Guardian about the British public school Eton:

"There were Etonians in Thatcher's first cabinet, but it appears that she didn't feel easy in their presence. In 1983, she sacked four of the most prominent Tory Etonians, prompting Macmillan's snobbish (and anti-semitic) mot about there being more Old Estonians than Old Etonians in the cabinet."

The point is that the UK cabinet (committee of senior government ministers) has, in the past, such as under the Prime Minister Harold Macillan (a.k.a. "Supermac") in the 1960s included many former pupils of Eton. Healthy government, eh? And it could happen again. David Cameron, likely Tory leader, is an Old Etonian, as is Oliver Letwin, former Shadow Chancellor (meaning he spoke for the Tories on finance issues, and is Gordon Brown's "opposite number"), though currently in the political wilderness, it seems. The current Shadow Chancellor, Cameron's mate, George Osborne only went to St. Paul's school. Educational, this site, isn't it?

Perhaps someone could explain why Macmillan's remark is "anti-semitic", though?

PS Just found (here) that Letwin is currently just Shadow Secretary of State for Environment, Food & Rural Affairs. Funny how his CV doesn't mention Eton.