15 was certainly considered old enough for a marriage witness. However, as the case I am about to detail shows in cases of death etc, a witness could be considerably younger.
My grandmother killed herself in 1901; my grandfather had gone to work; and the people remaining in the house were herself; my father aged 2, and his cousin who was visiting aged 8.
The coroner called the 8 year old boy as a witness, to the effect that there was no one else who could give evidence as my father was obviously too young, and in any case slept through the incident. The boy found her body and raised the alarm.
