The boy, named Roman, told the emergency services operator that his mom was dead because "she's closing her eyes and she's not breathing." Police and paramedics arrived at the house within thirteen minutes and managed to revive her.
Roman, his twin brother and a younger brother were in the home at the time.
Met Police Ch Supt Ade Adelekan said: "Hearing this call brings home the importance of teaching your young child their home address and how to call police or emergency services in an emergency situation."
You can listen to the 999 call at the link below...