Caption: A cartoon of Georges Lemaitre (1894--1966).
Now for a fine point in the history of astronomy: Who discovered the expansion of the universe and Hubble's law?
The sophisticated readers of Hubble (1929) (e.g., Willem de Sitter (1872--1934), Albert Einstein (1879--1955), Richard C. Tolman (1881--1948), Arthur Eddington (1882--1944), and Georges Lemaitre (1894--1966)) must have picked up the correct general-relativistic interpretation of the measured redshifts.
Famously, Einstein missed his chance of predicting the expanding universe from the Einstein field equations by assuming a static universe which he obtained by introducing the cosmological constant. His universe model is the static Einstein universe.
However before 1929, Willem de Sitter (1872--1934), Alexander Friedmann (1888--1925), and Georges Lemaitre (1894--1966) all found expanding universe solutions to Friedmann equation (which in turn is derived from general relativity). These solutions all obey the theoretical Hubble's law and, in fact, the theoretical Hubble's law follows directly from the Friedmann equation without needing solutions (e.g., Li-37--38) and Lemaitre showed this explicitly.
Note that Lemaitre had NOT discovered Hubble's law was obeyed by the observable universe. What he had shown was that if Hubble's law were true for the observable universe, then existing observational data gave values for the Hubble constant.
Nevertheless, Lemaitre had shown there was significant observational evidence for Hubble's law---which as aforesaid, he had theoretically discovered from the Friedmann equation. It seems likely that if Lemaitre's 1927 article had become well known, Hubble's law would have been called Lemaitre's law.
Unfortunately, Lemaitre's 1927 article was in French and was published only in the obscure Annals of the Scientific Society of Brussels. This may be why the article was NOT much noticed.
It seems likely that Lemaitre did NOT realize how important his Hubble's law work was in 1927 since it only appeared in a footnote in his article (Livio 2011). The lack of realizing the importance probably prevented Lemaitre from advertising his Hubble's law work.
Lemaitre himself was well known as to cosmologists---there were maybe 5 in the 1920s. So he could have advertised his Hubble's law work more than he did.
When the article was translated into English by Lemaitre himself and published in Monthly_Notices of the Royal Astronomical Society (MNRAS) in 1931, Lemaitre omitted the footnote as of being of "no actual interest" (Livio 2011). Actually, "actuel" in French means "current" and that is probably what Lemaitre meant by "actual." It seems possible that Lemaitre did NOT wish to give the appearance of claiming priority for the observational discovery of the expansion of the universe and Hubble's law and get into a piority dispute with Hubble.
Also, Lemaitre in 1931 was more interested in advertising his new primeval atom theory a forerunner of Big Bang theory.
Yours truly thinks and probably Lemaitre himself thought that he'd simply missed the boat on getting partial credit for the observational discovery of the expansion of the universe and Hubble's law.
However, in 2018, the IAU decided to give Lemaitre some credit and formally changed the name of Hubble's law from Hubble's law to the Hubble-Lemaitre law. Yours truly does NOT think the longer name will be much used. We've always called Hubble's law Hubble's law and it's shorter to say and write.