I did find this for Lily Smith in Sept 1964
SMITH LILY 80 BRENTWOOD 4A 354
It is Brentwood and not East or West Ham/Forest gate but the dates work. However that would mean Lily somehow found herself moving from Forest Gate into Brentwood area or maybe was sent to a hospital there! Perhaps it is a different Lily.
In your experience is it unusual for a death to be registered in a shortened name like Lily as she was actually christened Lilian Alice Ormesby (I have no idea where the Ormesby came from).
kind regards
Roger