I knew that young boys in the Regency wore dresses and ankle length drawers. However, I assumed they were breeched by the age of three.
The heroine in my new novel, Tuesday's Child, has a three and three quarter year-old son.
I researched children's clothes. Boys wore skeleton suits. The ankle length trousers fastened with buttons to a tight jacket that had a double row of buttons fastened down the front. Alternatively, the trousers were fastened to a shirt, so that the jacket could be left open to reveal frills down the front of a blouse, which had a wide collar edged with a frill.
I described young Arthur in his 'skeleton suit' and tried, unsuccessfully, to find out if the term was used in the Regency period.
After much more research I found out that boys were not breeched until they were about five years of age. Arthur now wears a gown with a high waist and low neck, ankle length drawers, and white stockings. When he goes out he wears a top hat instead of a bonnet that girls wore.
I still need to research fabrics - materials, wool, cotton, silk, plain, sprigged, patterned or tartan.