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:
Alexander Edward Herbert
Arthur Algernon Peter
Arthur Robert Edward -- my nephew!!
Leo Frederick Peter
Reuben Alexander
Theodore James Timothy
Vere Evelyn Michael (Arthur George & Ludovic)
Wilfred Hector (Hari Mohan Robert & Bertram "Bertie" William Vijay)
Girls:
Alaia Mei Hua (Arabella Xue Hua)
Cecily Charlotte Alice (Parker & Mirabelle Lula Rose)
Irah Louise
Lily Margaux (Henry Rupert)
Marina Linda Lavallin
Mia Rae
Sienna Grace (Albie James & Edie Dree)
Skylar Rose
Twins:
Ralph Muir & Basil Richard
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.