In 1919 the scholar A.S. Yahuda (Abraham Shalom Yahuda, 1877-1951, best known, I think, for his work on the relationship of the ancient Egyptian language and the Torah) lectured in Hebrew at Jews' College in London. Here is Yahuda:
Dayan Harris M. Lazarus (1878-1962) of the London Beth Din attended the lecture and while he had words of praise for the lecture generally, he felt that Yahuda had committed an affront to Jewish sensibility by giving this lecture with a bare head. So he fired off this letter to the Jewish Chronicle (July 25, 1919):
Lazarus says that he assumes that Yahuda has covered his head when visiting mosques and speaking to Arabs about their sacred literature. Should not respect be heeded to Jewish modes of propriety? He particularly found the fact that he was quoting biblical verses bareheaded to be objectionable. He thinks there were no gentiles present, and even if there were, well, there presence was mooted by the larger number of Jews, and therefore it is Jewish custom that ought to have been respected. Furthermore, felt Harris, Yahuda's display plainly contradicted that of another speaker, who explained that no one should think that Palestine reborn will become Westernized. It ends with a complaint about Zionists (Nationalists) flouting ancient Jewish customs.
Not surprisingly Yahuda did not agree that he did anything wrong. He wrote back (Aug. 8, 1919):
Yahuda responds to the charge that he showed "little deference for Jewish custom" as follows.
It happens that he personally has no preference for Jewish or Western customs, but always wishes to be considerate. Also, it was neither a religious service, nor a sermon, or even a religious lecture. It was "a simple lecture on a literary matter from a purely scientific point of view" that happened to be delivered in Hebrew.
He goes on to say that he hardly needs to quote halachic opinions about head covering, which state that head covering is permitted outside of "religious exercises." (He probably has in mind sources like the Maharshal.) Since the Dayan seems to be particularly perturbed that it was a Hebrew lecture, he is making the same mistake as as many others (i.e., the Ultra-Orthodox in Palestine) who consider speaking Hebrew to be a religious act. Hebrew is being reborn at the moment, and is not only restricted to prayer and learning, etc. So Lazarus either must side with the extremists or acknowledge that he is correct.
He then cites an unnamed "very pious and learned Rabbi in Jerusalem" (Rav Kook?) who was asked how it was possible to tolerate Hebrew-speaking by bareheaded people, and replied that if speaking Hebrew was a religious ceremony then simply speaking secular matters in it would be forbidden (i.e., and that plainly isn't true, ergo headcovering is not required when speaking Hebrew either).
He then says that he objects to Lazarus' characterization of him as "a man who does not mind hurting Jewish feelings, but who, when having intercourse with them, would make every effort to avoid hurting the feelings of non-Jews. Really," he says, "I always endeavour to behave with due courtesy to everyone."
And he continues: Besides, what is Lazarus talking about? Aside from the women [who were wearing hats, fashionable ones pinned to their hair, presumably] there were probably not even a minyan of men sitting in the audience with a covered head. So all the talk about sensibility, whose sensibility was wounded? A bareheaded Jew was talking to an audience of bareheaded Jews. Actually, he suggests that many of the audience would have considered covering the head on such an occasion hypocrisy rather than proper deference ot Jewish custom.
After dismissing the presumption that he must have adhered to Arab customs and paying them respect when discussing their sacred literature with them, he addresses what he realizes was the Dayan's major objection: quoting pesukim, biblical verses. Lazarus wrote "passages from the Bible verbatim." Yahuda says that his quotations were not, in fact, verbatim, but he "adopted some alterations of the traditional text." This is most interesting, and I wish he had explained. It sounds like he was either following halacha in not quoting scriptural verses by heart, or perhaps even not being willing to recite them bareheaded. Alas, he does not explain. But since he is annoyed with the letter, he gets in a little dig about how Lazarus seemed not to notice such alterations in the text despite his weekly reading shenayim mikra ve-echad targum. On the other hand, from reading on it seems that Yahuda meant that his quotations were of emended verses. If that's the case, he's ridiculing Lazarus' seeming insistence that he cover his head to read emended pesukim which "from an orthodox point of view, gives better ground for challenge."
Finally, he is sorry that the only takeaway Lazarus got was that his head was uncovered. He agrees that the New Palestine should not be frivolously Westernized, and that's why he thinks that Orthodox customs imported from European Christianity, such as the insistence of covered head like among Catholic priests, also have no place there. (Yahuda was Jerusalem-born, but descended from an Iraqi and, I think, Indian Jewish family.)
In the same issue someone called E. Carmel wrote as follows:
On the question of "Hatless Hebrew" he says that as a living language people cannot be expected to wear a hat when speaking it, otherwise it could never be spoken while bareheaded as at, for example, the barber. Also, doesn't the Dayan know that the Vilna Gaon wrote that only prayers are prohibited without a hat? Quoting the bible "as illustrations of poetic forms cannot be regarded as prayers." Finally, like Yahuda said, the Dayan did not object to the content of the lecture - "which was enough to shock anyone adhering to strict traditional orthodoxy" - but whether or not Yahuda was wearing a hat. He says this reminds him of the religious man trying to convince an atheist that there is a God because it says "And God spoke to Moses" in the Bible.
The following week (Aug. 15, 1919) Dayan Lazarus made his reply:
He says that he made a point about Jewish etiquette, and Yahuda took it as a criticism of his lecture. In fact, he said very nice things about the lecture. He says that while Yahuda may have "occasionally introduced" some "most indifferent variations" he cannot seriously claim that he was not citing "passages from the Bible verbatim" without quibbling. Furthermore, he never claimed anything about deference toward the Hebrew language as such (I agree).
He says that it is specifically because of who Yahuda is, an eminent scholar, and one who "is ever upholding the Jewish claims for respectful consideration," and because he is acquainted with "the Oriental outlook," he felt that Yahuda should have considered even the minority when citing "long passages of the Bible with the frequent occurrence of adnut" - God's name - because he is who he is and the occasion was what it is is why he brought it up.
He tries to add some more conciliatory words, noting that among the audience there were in truth few who were as able to appreciate the lecture as himself, noting that he had recently been studying Yahuda's "splendid Arabic edition of Bachya's Al-Hidaya" and doing so "attentively and gratefully." Finally, he says that his comment about "many a Nationalist Jew" was not aimed at him, but at them. He concludes by saying that it is easier to be modern and it requires less courage to go along with the majority than to remain steadfast with the minority.
 On the one hand this isn't the greatest place for a note, but I don't want it to get lost later one. While I haven't read very much of Yahuda's work, but I've read enough to know he was an opponent of Higher Criticism; not totally denying it's accomplishments, but definitely a critic of what he felt where its excesses and complications. Furthermore, his work to show that Egyptian is found in abundance in the Pentateuch was aimed at putting it in its proper historical context - the time of Moses and the Exodus from Egypt. See, e.g., The Accuracy Of The Bible by A.S. Yahuda (1935).
Finally, a few months later (Oct. 10, 1919) German-American Reform rabbi Gotthard Deutsch added his views:
Deutsch goes on to say that Vilna Gaon was quote in error, because he did not say that it is a "religious ceremony" [for prayer]. The point is that it is an Oriental custom of respect and decorum, not a religious one, and it is exactly comparable to wearing a collar and tie (or removing it). He refers naturally to his own article in the Jewish Encylopedia, as well as the aforementioned Maharshal, and his beloved Sde Chemed (if Gotthard Deutsch is writing an article, he is quoting the Sde Chemed) that there is no prohibition against praying bareheaded although, of course, they are against it.
He continues to reiterate that covering the head is a custom, not a religious requirement, and long after covering the head in public has disapppeared among Western Orthodox Jews, they nevertheless retained the covering custom in the synagogue. He refers to a writer from Budapest writing in Der Israelit in 1902 who complains about a "himmelscrelende Chillul Hashem" that in his city there are schools where religious instruction is given bareheaded. New York's Morgen-Zhurnal calls such things "a Schande fur a heilige Sprach zu machen ihr so wochedig" and the Tag, which is not so frum, as it was "put on the index by the Orthodox rabbinate for issuing an issue on Sabbath" is milder still, and refers to it as "a Zeichen fur idischen yiras hakavod."
He goes on to cite various sources, such as R. Menachem Azariah Meir Castelnuevo who permitted performing shechita while bareheaded (link), refers to the preference of the Karaites and Yemenite Jew to pray barefoot, and so on. He also mentions an interesting case of an 18th century German physician who wrote about ways that Jews can improve their health, and says that their headcoverings ought to be of light material. He does not advise that infants have their heads uncovered, out of respect for the religious scruple. He also refers to Wolf Eybeschuetz, son of R. Yonasan, who was indicted by R. Jacob Emden for, among other things, riding in his carriage with his hat on the seat instead of on his head. He even refers to an incident from folklore about how one of the Slavuta printers was forced to run a gauntlet, and paused to pick up his yarmulke.
He the notes that interestingly while the men cling tenaciously to something which is mere propriety and custom, actually for women it is law. And observance of that has basically disappeared, even among the wives of many men who advocate the covered head (he is careful to state that he doesn't know one way or the other what Dayan Lazarus' wife does). He ends by stating that all of the above is for informational purposes, not to advocate for a particular reform.
Finally, some words about Dayan Harris M. Lazarus. Here are two photos of him (link):
First, it seems pretty clear that he is in fact bareheaded in the second picture (with his wife, who is wearing a hat!). I believe this puts some better-needed context. Dayan Harris was hardly a Jerusalem extremist of 1919. In fact, Lazarus, who was born in Eastern Europe, is quoted in Bruce Mitchell's Language Politics and Language Survival: Yiddish Among the Haredim in Post-War Britain (pp. 11-13) writing in the Jewish Chronicle in 1946 that "the teaching of Gemara in Yiddish destroyed its whole spirit because Yiddish lacked the technical language resources that were so vital to the proper elucidation of the meaning of their sacred writ." (In response to criticism from a young Cyril Domb that he was attacking Yiddish, and that the bastions of Talmudic scholarship in Eastern Europe evidently did alright with Yiddish as their language of study, he replied that he did not mean to do so, but was only offering "a pedagogical constructive criticism.")
It surprised me that he didn't even mention that it would be appropriate to cover the head while lecturing in a place like Jews' College, responsible for producing many of Britain's rabbis (even if most of them were really Reverends). Such was the time.
 I tried to contact the copy-right holder of these images, evidently a descendant or family-member, without success. It is my hope that if he should chance upon this post he will be glad that I used these images. If not, I will of course respect his wishes if he asks me to remove them.