A man approached her from behind and shoved her to the ground at about 13:30 GMT in Hanwell Cemetery, west London.
The suspect made off with her bag which was later recovered by a member of the public, but the purse had been taken.
The victim suffered minor injuries in the incident but did not require hospital treatment.
Police have released a CCTV image of the suspect, who is described as skinny, about 5ft 9in tall, wearing a black scarf covering his face, a grey hooded top, a black coat and jeans.
A Met Police spokesman said: "The robbery took place in broad daylight and police are keen to speak to members of the public who saw a man matching this description, walking briskly away from the scene, with his face covered and hood up."
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