Prod. 2138 - The Sword in the Stone - Seq. 01.1 - "Introduction of Merlin, Owl, Wart and Kay"
Animated by Dick Lucas, Eric Cleworth, John Lounsbery, Ollie Johnston (Merlin and Archimedes the Owl), Milt Kahl (Kay and Wart) and Hal King. John Ewing reuses some Lounsbery animation.
This FINAL draft of 6/14/1963.
Milt basically singlehandedly coined the final model on all the characters, so based on previous experiences, it seems plausible that Ollie and Milt led the animation, with Lounsbery on the wolf, then followed by Cleworth, Lounsbery and King on the principals...
Please feel free to contradict me through the comments! I may make some assumptions that take me way out on a limb, just to get your reaction!