I think (off the top of my head) it would be a formation involving:
617 - formed 1943
230 - unlike other naval sqns, formed by amalgamating flights rather than renumbering a squadron
216 - formed early 1918 as 16(N), although its precursor organisation 'A' Squadron RNAS might disqualify it
120 - 1 January 1918 formation date
If 216's predecessor unit disqualifies it, then I think it'd be 99, which formed in August 1917.