Thimelby was born in
Irnham Hall in Lincolnshire. Her parents were Mary (born Brookesby) and Richard Thimelby. Her ancestors were known for harbouring Catholics hiding from the Protestant authorities. The families were discriminated against as Catholics and fined regularly. Irrespective of this the Thimbleby's kept a full time priest at the home. Her father wanted to have at least one of his children to follow a religious life and Mary decided that she would like to be a nun. She was a notable letter-writer and she was unanimously voted in as the new Prioress after Margaret Throckmorton died on 26 October 1668. Sister Gertrude died in 1668. Thimelby died in
Leuven in 1690 after resigning from her leadership role a week before. ==References==