My youngest son has been listening to a story CD every night recently of a wonderful puppet show we saw last year, an adaptation of "The Arabian Nights" by The Theatre of Widdershins. He has been retelling the story with great expression, and today he asked me to film his production, which he acted out with teddy bears. The language, as the lead character travels 3000 miles from the city of Baghdad to Samarkand and back again in search of his fortune, was rich and the intonation, expression and humour he used in his storytelling was wonderful.
My theory is that with such evidence of oral language development, though their writing might not be comparable with their schooled peers at present, as the boys' fine motor skills develop, what is coming out of their mouths will one day flow out of their pens. It is different at home, with more focused interaction with adults and rich conversational opportunities, to a school classroom where children's chief interaction is with their peers, and a lot of teacher speak is directional.