Metchosin also managed 18 / 18½ and was PMing me his answers while I was sending him the full list.

To speed things up:
Beatles: Hollies: Ken Dodd or Womack & Womack: Manfred Mann: Shakin' Stevens or Frankie Vaughan: Crosby: St Cecilia: Elvis: Jim Reeves: Simon & Garfunkel: Beatles: Elvis: Meatloaf: Frankie Laine or Tennessee Ernie Ford: Louis Armstrong, Frankie Vaughan or Sinatra: Beach Boys: Cliff Richard: Thin Lizzy or The Pogues and The Dubliners: Michael Jackson or Devo (different titles): Elton John.
Does that make it too easy ?