Mono recordings - two questions...

If we're talking great mono, I also recommend any of the LPs sold via "Sam's Club", which is based in France.  I forget the name on the label of the production company.  All the Chet Baker recordings are to die for, in mono.  (Recorded during Baker's sojourn in Paris, I think.) They've produced maybe 8 or 10 LPs thus far, no losers among them.
Also, the original "Ella and Louis" recordings are sublime.

Thanks for the tip, OP. I will listen to that cut on the CC album in the next few days. Not that I really care, but it’s "LewM", not LewN. If you were searching for me, in order to communicate privately, that would make a difference, I suppose.

I've got both the original Liberty mono recording of "Julie is her name" and a 45-rpm re-issue. Because my copy of the original pressing is not in great shape, I listen to the 45 most often.  I really should expand my repertoire of Julie London LPs, beyond this one.  She was really quite talented, a fact which often gets obscured due to her obvious physical attributes.  As an amateur vocalist, I can tell you that "Laura" is not an easy song to sing, and she does a great job on it, one of my favorite renditions.

bdp24, Aren’t all stereo cartridges based on sum and difference? Perhaps Decca’s behave differently because both channels share a single common ground. Interesting story: Many, many years ago, both I and my best audio friend owned Decca London cartridges. We were both tinkerers, and after we discovered that you could easily remove the top plate on the London and thereby gain access to the innards, we also noted that there were tiny set screws inside that one could play with. We decided to play with them in order to get best sound. After some fooling around each of us independently ended up with adjustments that we liked best in our respective systems. It was only a few weeks after that, and I forget how it happened, that we discovered we had each turned our stereo London cartridges into mono cartridges. The experience should have told us something, but it didn’t. (Maybe we were playing mono LPs, for example, to explain our aural preference.)

I own both the stereo and the mono versions of Something Cool, and the mono wins; it's no contest.
I own the Chris Connor too, and it's great.  However, these are examples of small group jazz with a vocalist at the center; not much need for stereo, musically speaking.

What Pryso said.  So far, my research tells me that there are very few "true mono" cartridges being sold these days.  Some that probably ARE true mono are the Miyajima series, then EMT makes one or two. I am sure there are more, and now perhaps we will hear about those. If you are on a budget, don't worry about this issue at all.  Just buy a bridged stereo cartridge or do as Tim (Pryso) suggests.  (Don't try to solder the jumper wire; you'll fry the coils.)  I would add Ortofon to Tim's list of companies that market mono cartridges derived from one or another of their stereo cartridge models.

The reason you could find a Julie London LP in mono is because most of her work was done in the mono era of LP production (early 50s to mid-60s).  I very much doubt that you can find mono recordings of the artists you list in your last sentence, because they are very much with us in the here and now, in stereo.  I have some Julie London mono LPs; I agree it works well in mono.  But I would not agree that you need to limit yourself to solo performances; most small group jazz and chamber music does very well in mono, and somehow the brain picks up spatial cues from mono surprisingly well.

I thought at one point in reading your post that you were going to ask about listening to mono through one speaker of a stereo pair (assuming your system is basically stereo), vs listening to a stereo pair of speakers each of which is reproducing the same mono signal, simultaneously.  Anyway, I take the latter approach.  Then there is the endless debate about using a mono cartridge vs a mono switch on your preamplifier, or both.  It is true that mono signals are generated from lateral movement of the stylus, exclusively. Vertical motion generates noise from the LP groove, only. Whereas true stereo reproduction requires that the music signal is encoded in both planes.  Thus stereo cartridges tend to reproduce noise from mono LPs, and many think that using a mono cartridge or a mono switch is the only way to go. (Either way, you are cancelling the signal due to vertical motion of the stylus by bridging.)