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:
Caspar Riprand Roderick Maria (Josephine)
Hugh John Mavourn (Edward Thomas Philip)
James Edward (Isabella Rose)
Lando Steven
Myles Robert
Pietro Stefano Aditya
Philip Francis
Rudolph Valentine -- grandfather is Valentine
William Oliver Grosvenor
Girls:
Amelia Charlotte
Ember Philippa Sage (Grace)
Harriet Georgiana Rose (Matilda)
Margot Persephone Iris
Martha Morven Alexandra (William "Bill" Pridmore John)
Nellie Avis
Nylah Maria (Thomas Douglas, Nico Anthony & Ruairi)
Phoebe Lily
Rose Amelia (Wilfred Sonny & Eiza Jennifer)
Theresa Mary Elizabeth
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.