Green’s Dictionary of Slang

1. the female breasts.

2019		P. Baker Fabulosa 299/1: willets breasts.
2023		R. Milward Man-Eating Typewriter 29: [A]ny pop who dared criticise her lavvystyle [...] or the symmetry of her willets‡ [f.n.] ‡ ‘Breasts,’ Howling exclaimed, cupping his own lopsided tits.

2. used fig., a heap, a pile.

2023

R. Milward Man-Eating Typewriter 38: I wasa forbidden from [...] playing beyond the duey rubble-willets.