Which pair presented an electron-pair account relating molecular geometry to valence-shell electron arrangements in 1940?

Explanation

Nevil Sidgwick and Herbert Powell presented their electron-pair account of stereochemical types in 1940. This related arrangements around central atoms to valence-shell electron pairs and helped prepare the way for later VSEPR treatments. The question specifies this pair and work, without asserting that no related idea existed anywhere earlier.