This very unexpected selection is a real treat for several reasons. At the top of the list is seeing him not playing Anthony Newley with all the attendant quirks and mannerisms, but rather a full-blown character, without a Newleyesque twitch in sight, something he seemed to get away from in his later years. Also, this clip goes beyond the musical number and includes the following dialogue scene which I decided to keep in, because (again) it's fascinating to seem him play such a genteel, almost effete character, separate from anything we're used to seeing. But mainly, he's a total joy in the number. It's not a starring role (though appears to be a substantive one), yet he doesn't phone it in, but seems to be taking great pleasure in it -- not just in his singing and actor, but even in his dancing -- taking what could be a somewhat-caricatured, goofy part and makes it actually touching and affectionate.
Among all this research, one thing I noticed from coming across all the various videos I've found recently of Anthony Newley (including quite a few I haven't posted here...) is that -- whatever one thinks of him as a performer, loving his style or being bothered by the larger-than-life quirks -- he is a seriously talented, meticulous performer, most especially as a stage performer. Keep in mind that he'd been performing since he was a child actor, starring as the Artful Dodger in movie version of Oliver Twist, directed by David Lean. And this selection here does a solid job of making that craft clear. Stripping all that's "usually Newley" away, it's just simply a charming, graceful, lovely -- and deeply professional -- performance.