There is a chance that if Joyce was baptised that the name of the father is a side note to the baptismal entry in the register. Mossley in the 1920s would have been a fairly close knit community so the name of the father might well have been known and I've known cases where the vicar/priest would add the note perhaps as a reminder and perhaps for his successor. So it's always worth looking for the baptismal record. You would need to look at the registers or a microfilm because the note may not show on a handwritten copy taken from the register. The age of her mother suggests he might well have been a married man.