Below is a round-up of the birth announcements from British newspapers. Sources include a national paper (The Telegraph, The Times) and a broad range of local newspapers from across England, Wales, Scotland and Northern Ireland.
Sibling names are in brackets. No official surnames are included; any name ending in a surname is actually a middle name.
Boys:
Adam John Christian (James)
Christopher Buchanan Weld "Kit"
Frederick Oswald Richmond "Ozzie"
George Castell
Henry Arthur James
Leonidas Theo (Daphne Anna & Marios Demetrios)
Marley Phoenix Robin (Violet)
Ruairi Jowan
Walter Inman (Margot India)
William
Girls:
Beatrice Mary Lucinda
Cosima Florence Isabella (Matteo)
Frankie Rose (Thea & Willow)
Millie Victoria Eleanor (Mary)
Sienna James
Zahra Margaret (Tabitha Alice)
Media Personality Birth Announcements:
[g] Eva Sylvie [Pete Sandiford]
[b] Frank Alfred Odysseus "Frankie" (Wilfred Lawrie Nicholas "Wilf" & Romy Iris Charlotte; half-sibs: Milo Arthur, Cassia Peaches, Theodore Apollo, Lara Lettice & Stephanie) [Boris Johnson]
I cross-reference older BAs to find the full names of the siblings, however often they are missing (especially the eldest siblings, or for half-siblings) which explains why you will sometimes see something like: George Henry (Lucy, Emma & Jack Arthur). "Lucy" and "Emma" may well have middle names as well; I simply cannot find them online.