Actually, it's another from Winston Churchill (who as I remember
changed political party himself, probably at age 30).

Actually, it's probably not. This from the authoritative Churchill Centre
website http://www.winstonchurchill.org/i4a/...fm?pageid=112:

"If you're not a liberal when you're 25, you have no heart. If you're not a
conservative by the time you're 35, you have no brain." There is no record
of anyone hearing Churchill say this. Paul Addison of Edinburgh University
makes this comment: "Surely Churchill can't have used the words attributed
to him. He'd been a Conservative at 15 and a Liberal at 35! And would he
have talked so disrespectfully of [his wife] Clemmie, who is generally
thought to have been a lifelong Liberal?"

--
-Elliott Drucker