Considering that fathers were often virtually absent from their children’s rearing, this children’s hour could be exactly the case of the Holmes father, who was most probably busy managing the estate but devoted some time in the evenings to his sons. The book by Judith Flanders mentioned mothers who, contrary to the convention, were actively present in their children’s lives, feeding them, washing them, playing with them—i.e. doing the things a nanny or maid was supposed to do. It was frowned upon. Perhaps the Holmes mother was one of those unconventional mothers :)