On 09 Mar 1709 [her grandfather] Ralph Montagu 1st Duke Montagu (age 70) died. He was buried at Westminster Abbey [Map]. His son [her father] John Montagu 2nd Duke Montagu (age 19) succeeded 2nd Duke Montagu, 4th Baron Montagu of Boughton in Northamptonshire. [her mother] Mary Churchill Duchess Montagu (age 19) by marriage Duchess Montagu.

On 05 Jul 1732 [her father-in-law] George Brudenell 3rd Earl Cardigan (age 46) died. His son [her husband] George Brudenell aka Montagu 1st Duke Montagu (age 19) succeeded 4th Earl Cardigan. Mary Montagu Duchess Montagu (age 21) by marriage Countess Cardigan.

On 06 Jul 1749 [her father] John Montagu 2nd Duke Montagu (age 59) died without surviving male issue. Duke Montagu extinct. His estates were inherited by his daughter Mary (age 38) and her husband [her husband] George Brudenell aka Montagu 1st Duke Montagu (age 36) who changed his name to Montagu from Brudenell. Monument in St Edmund's Church, Warkton [Map]. Sculpted by Louis Francois Roubiliac (age 46). Erected by his widow, [her mother] Mary Churchill (age 59), the daughter of the 1st Duke of Marlborough, who stands at the left hand side of the monument.

On 14 May 1751 [her mother] Mary Churchill Duchess Montagu (age 61) died. Monument in St Edmund's Church, Warkton [Map]. Sculpted by Louis Francois Roubiliac (age 48). Erected by her Daughter, Lady Mary Montagu. The monument is adorned with figures representing the three fates of Clotho-, Atropos- and Lachesis-, arranged to show the cutting of Mary's life thread, and Lachesis' dismay at it being cut short. Three putti also figure on the monument, one of whom holds the spindle from which the thread was cut.

Clotho-: Clotho- is one of the Three Fates. She spins the thread of human life.

Atropos-: Atropos- is one of the Three Fates. She cuts the thread of human life.

Lachesis-: Lachesis- is one of the Three Fates. She measures the thread of human life.

On 20 Oct 1768 [her brother-in-law] Robert Brudenell (age 42) died.

On 11 Apr 1770 [her son] John Montagu 1st Baron Montagu (age 35) died unmarried. Baron Montagu of Boughton in Northamptonshire extinct.

On 01 May 1775 Mary Montagu Duchess Montagu (age 64) died. Monument in St Edmund's Church, Warkton [Map]. Sculpted by Peter Mathias Van Gelder (age 33). Mary's monument is more decorative that her parent's; Rococo. The composition of the monument centres around an ornate funerary Urn, which stands upon a Pedestal containing an inscription to Mary. To the right sits a grief stricken woman, inconsolable over the loss of an aristocrat considered a great benefactor to the poor and needy. In her left arm she cradles a baby, and a second, tearful child sits at her feet. To the right of the woman is that of an older woman draped in a shawl, who gently caresses the hand of the first babe. To the left of the Urn, an angel comforts the mourners, pointing to heaven.

On 23 May 1790 [her former husband] George Brudenell aka Montagu 1st Duke Montagu (age 77) died. Duke Montagu extinct. His brother [her former brother-in-law] James Brudenell 5th Earl Cardigan (age 65) succeeded 5th Earl Cardigan. Elizabeth Waldegrave Countess Cardigan (age 31) by marriage Countess Cardigan. On His grandson Henry James Montagu Scott 2nd Baron Montagu (age 13) succeeded 2nd Baron Montagu of Boughton in Northamptonshire. Jane Margaret Douglas Baroness Montagu by marriage Baroness Montagu of Boughton in Northamptonshire.