I do believe that C-3PO, while voiced by a male, was intended to be deliberately androgynous; he is plainly based on metropolis’ android (gynoid?), which is plainly feminine. While it’s all fine and good to pick on the British accent for lacking manliness, there are certainly deliberately androgynous affectations added to Anthony Daniel’s speech pattern.
C3PO has always reminded me of Stan Laurel (the thin one of Laurel and Hardy). Stan’s voice could get high pitched but he wasn’t gay.