here is Phil Tanner who was from TheGowerPenisula and english speaking part of wales, illustating my point a liting or diddling a tune and then singing a wassail, this shows the influence of a custom often associated with ireland diddling, and a wassail song , wassailing was also common in southwest and other parts of england
https://www.youtube.com/watch?v=xqCxKtHr778 here is lilting or diddling from ireland https://www.youtube.com/watch?v=qnUOq0euqYQ using the same modes as and here is a cornish wassailhttps://www.youtube.com/watch?v=YytajAIlJ2w