I think I was old enough to come in at the start of the dreary social commentary phase (Honor Arundel/Joan Lingard/later KM Peyton) but what I recall was there was still plenty of fantasy about but it got grimmer elements bolted on (eg A Game of Dark, the William Mayne one where the protag escapes into fantasies of attempting to kill a "Worm" which digests its prey in acid slime, to escape the looming conclusion that he's actually the son of the woman he regards as his sister, but it's entirely possible that his father remains the same person.)