Olivia has a portrait of her and on the reverse Mary Hodgson, née Gillett, Trotter wrote: “Mrs Watts, née Maria Churchill, my great grandmother.  M.H.T.”

From her entry in the Sherborne marriage register, she was (then) of the parish of Sherborne.
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I wonder if this burial entry is hers:

First name(s) Mary
Last name Watts
Age 72
Birth year 1751
Death year 1823
Burial year 1823
Burial date 15 Dec 1823
Burial place Sherborne
County Dorset
Country England
Source Dorset Burials 1
Record set Dorset Burials
Category Birth, Marriage, Death & Parish Records

I am ordering an image of the register entry in the hope that it has a little more information.  Regrettably it doesn’t.

The indications from his will is that she did not predecease him, so the above is a little more likely to be her burial.

The birth year of 1751 means she would have been 16 at marriage.  Not uncommon at those times, viz Isabella Lybbe in 1730.
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With this birth year of 1751, searches were made for baptisms in Dorset of a Mary or Maria Churchill from 1746 to 1756 and:

FamilySearch found:

(a) 2 Jun 1749, at Wareham, Mary Churchill, dau. of Thomas and Elizabeth,

(b) 13 Mar 1754, at Sherbourne, Mary Churchill, dau. of John and Agnes,

(c) 13 Nov 1755, at Dorchester, Mary Churchill, dau. of Joseph and Christian,

(d) 14 Mar 1755, at Blandford Forum, Mary Churchill, dau. of Robt.

and FindMyPast found:

(a) 5 Nov 1747 at Sherborne, Mary Churchill, dau of John and Agnis [sic],

(b) 2 Jun 1749, at Wareham, Mary Churchill, dau. of Thomas and Elizabeth, though she was buried later that year on 27 Jan 1749 (years then ended on Mar 25th).

(c) 14 Mar 1755, at Blandford Forum, Mary Churchill, dau. of Robert,

(d) 15 Nov 1755. at Dorchester, Mary Churchill, dau. of Joseph and Christian.

Looks like the people are the same, but the dates are mangled!

But the Sheborne baptism is tempting.

FindMypast also had two other Sherborn baptisms for the parents of John and Angis:

Sarah in 1749

John in 1751

This led to finding this possible marriage for her parents:

Record set Dorset Marriages
Gender Male
First Name John
Last Name Churchill
Marriage year 1746
Spouse's First Name Agnes
Spouse's Last Name Pitman
County Dorset
Country England
Place Sherborne
By licence or by banns -
Description Blessed Virgin Mary
Marriage date 21 Aug 1746
Category Birth, Marriage, Death & Parish Records
Subcategory Marriages & divorces

There is also a record of the Bond for the licence issued the day before this marriage.
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NA

Their marriage transcript:

Record set Dorset Marriages
Gender Male
First Name Robert
Last Name Watts
Marriage year 1777
Spouse's First Name Mary
Spouse's Last Name Churchill
County Dorset
Country England
Place Sherborne
By licence or by banns Licence
Description Abbey Church of the Blessed Virgin Mary
Marriage date 09 Aug 1777
Notes Soap-boiler
Parish (original) otp
Spouse notes -
Spouse parish otp
Witnesses Thos WATTS, Betty CHURCHILL
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The marriage licence transcript:

First name(s) ROBERT
Last name WATTS
Birth year -
Bond day 7
Bond month Aug
Bond year 1777
Marriage year 1777
Place SHERBORNE
Groom's first name(s) Robert
Groom's last name WATTS
Groom's age -
Groom's occupation -
Groom's parish Sherborne
Groom's county Dorset,England
Bride's first name(s) Mary
Bride's last name CHURCHILL
Bride's age -
Bride's parish -
Bride's county -
Bondsman 1 MILLER Samuel, Sherborne
Jurisdiction The Dean of Sarum in Wiltshire, Berkshire,
Dorset and Uffculme, Devon
County Dorset
Country England
Record set Sarum Marriage Licence Bonds
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