most definitely staunchly Liberal. I used to live and vote there once upon a time.
Are there a handful more conservatives there percentage-wise than, say, the UWS or the Bronx let's say? Sure, some financiers and some "old money" add a few more sprinkles of conservatism in this exceedingly "blue" area. It's still a "tallest midget" argument at best.
You'd have to be left of Mao to posit the Upper East Side of Manhattan as "strongly Conservative". It's a deliberately misleading characterization.