I can’t really help much with the dates. Remington and UMC combined in 1912. Some have “London” on the label and some don’t. Remington UMC Co. Ltd. (England) closed in 1946. Palma was named for the Palma Matches and they advertised them as having superior accuracy. If you come up with more/better info, kindly share it with me!
Here’s a few codes and descriptions. I hope it helps.
R11K .22 Short Hi-Speed “Kleankote”
R14L .22 Long lubricated
R17L .22 L.R. lubricated
R19 .22 L.R.
R20 .22 Klay Bird (shot)
R21 .22 L.R. Hi-Speed
R23 .22 L.R. Hi-Speed hollow point
R23L .22 L.R. Hi-Speed hollow point lubricated
R24H .22 L.R. shot Hi-Speed
R28S .22 Winchester/ Rem Special (.22 W.R.F.) Hi-Speed
R31A .22 Auto Rifle R.F. (.22 Win Auto)
R54PB .22 L.R. Palma Hi-Speed
R54PM .22 L.R. Palma Match