RCLPL has two versions:

1. Thos Coster = Maria Churchill

2. Thos Coster = ? Watts, dau of ? Watts and ? Churchill

Have no idea which is right!  (If either)
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The 1841 census shows a Mrs Maria Coster in York Terrace, St Marylebone with Thomas and their daughter Eliza.  Assuming this is correct, this makes it very probable that Eliza’s mother was Maria.  Other evidence, from the miniature in Olivia’s posession - see Maria Churchill her mother - has it that she was born Maria Watts, taking the same forename as her mother and thereby confusing one or two people, me not least of them.
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In the 1851 census she was stated to have been born in Shoreham, Worcs.  I can well see an enumerator getting confused between Shoreham and Sherburn though how Worcs crept in I don’t know, amd there is no Shoreham in Worcs, or at least not in the Phillimore index of parishes.

She was married in Sherborne, as were her parents who had three other childred there, according to the transcipts on FindMyPast.  I wonder if the transcripts were fropm the register or from the Bishop’s Transcripts?
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She was alive in 1855 at her daughter’s marriage but her subsequent life is not identifiable.

I have found a death certificate for a Maria Coster aged 93 on 2 Jan 1872 in Windsor.  She was an Almswoman pensioner from George 3rd’s establishment.  This was not Maria Coster as she was only 85 from the 1851 census.

And there is a Maria who died in Halifax aged 83 in qtr ended Mar 1868.

And (TFPL, Jan 2012) there is this death, though with no age:

Surname   First name(s)   Age   District   Vol  Page
Deaths Dec 1860   (>99%)
Coster Maria Frances Hastings 2b 19

And (TFPL, 2015) this death, again with no age:

First name(s) MARIA
Last name COSTER
Gender Female
Birth day -
Birth month -
Birth year -
Age -
Death quarter 2
Death year 1853
District AMESBURY
County Wiltshire
Volume 5A
Page 141
Country England
Record set England & Wales deaths 1837-2007
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And, even more likely, this death:

First name(s) MARY
Last name COSTER
Gender Female
Birth day -
Birth month -
Birth year 1799
Age 78
Death quarter 3
Death year 1877
District MARYLEBONE
County London
Volume 1A
Page 315
Country England
Record set England & Wales deaths 1837-2007
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June 2016, TFPL: Her death date was in fact found to be on 11th Jan 1868 in Halifax where she must have been staying with her elder daughter, the recently titled spouse of her son-in-law, Lady, or Dame, Maria Churchill Edwards née Coster.  This was from the probate index, which I searched from 1851, when she was alive in the census, and for the next 17 years; details are in the Will Notes.

Her death index:

First name(s) MARIA
Last name COSTER
Gender Female
Birth day -
Birth month -
Birth year 1785
Age 83
Death quarter 1
Death year 1868
District HALIFAX
County Yorkshire
Volume 9A
Page 280
Country England
Record set England & Wales deaths 1837-2007
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Jun 2016, TFPL: she was at last found in the 1961 census by going for the address of York Terrace.  This revealed that her name had been transcribed as Costen, which though unclear, was not what the enumeratgor had written.

Anyhow this said that she was born in Sherborne, Somerset which is good enough and in 1783.

Various dates for her birth:

In the 1861 census she was 78, so born in 1783,

In the 1851 census she was 64, so born in 1787,

At death she was 83, so born in 1785.

A mean average of 1785 seems fair?

But I wonder if the christening of her sister Martha in 1783 might not have resulted in a renaming to Maria and Martha then disappears, with no death or marriage record.  The entries in the register (or bishop’s transcript) are all very egual as if thery had all brrn written at the same time, possibly from notes.  If this is what happened, it could just be possible that the notes had Maria written and this might have been copied as Martha.  We shall never know what is the cause of a Martha being baptised and a maria being the second child who survived to adulthood.  What we do know is that these three sisters named in their father’s will, kept in touch and remembered each other at lease in the naming of some of their children.  Maria definitely seems to have been thoroughly treated as a duaghter, and sister, of the family.
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The probate index for 1868 has:

COSTER Maria
Effects under £5,000.
Resworn at the Stamp Office June 1868: Under £6,000.
Resworn at the Stamp Office July 1868: Under £7,000.

“7 March  The will of Maria Coster of 27 York-terrace Regent’s park in the County of Middlesex widow deceased who died 11 January 1868 at Pyenest near Halifax in the County of York was proved at the Principal Registry by the oath of Thomas Oliver Watts Coster of 137 Harley-Street in the County of Middlesex aforesaid Esquire the Son one of the Executors according to the Tenor of the said Will.”

Her will has been ordered.  I am wondering if she said anything about burial and her husband’s.
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In her will by writing that the executors were to be the same as for her husband’s will, she effectively appointed her son Thomas, her son-in-law Sir Henry Edwards and her nephew William Churchill Longman as executors.  Her will was dated 14 May 1865.

She made bequests to:

Her son Thomas Oliver Watts Coster,
Her daughter-in-law Mary Ellen Parry Coster,
Her daughter Maria Churchill Edwards,
Her daughter Eliza Gillett,
Hew two nieces Mary Longman and Sarah Grant.
The two brothers of her neices Robert Longman and Wm Churchill Longman
Mary Thick, her sevant for ‘her kind attention to me’.

The witnesses to her will were J H Plowes and Eliza Plowes, both of 39 Youk Terrace, Regents Park.
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There is a marriage register entry for Sherborne, Dorset on 30 Jul 1805 as follows (photocopy has been obtained):

“No 130: Thomas Costar of Wood Street, Cheap Side, London, bachelor and Maria Watts of Sherborne in the County of Dorset, spinster, were married in this church by licence this thirtieth Day of July in the Year One Thousand eight Hundred and five by me John Parions (?) curate.
“The marriage was solemnised between us (signed) Thos Coster, Maria Watts in the Presence of Sam Foot and C F Foot.”

The trouble with this marriage record is that it is a bit early compared with the births of their known three children from 1816 on.

The next step would be to see if the licence can be found, possibly obtained in London.  It might have a little more information.  Subsequent note: Nothing found in Foster’s edition of Chester’s edition of London marriage licences.  So, let’s try Dorset; SoG has the odd book of such.
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2016: Additionally Frances Rouse has found this notice in the The Salisbury and Winchester Journal. Monday August 5, 1805. p.5. Issue 31602. British Newspapers Part III. 1780-1850
“Salisbury. Monday August 5 1805.
“On Tuesday was married Mr Thomas Coster, of Wood-street, Cheapside, London to Miss Maria Watts, second daughter of Mr Robert Watts of Sherborne.”
(A photocopy of this too has been obtained.)
(The previous Tuesday to Monday Aug 5th was indeed the 30th July.

This confirms the above church record, such that the marriage dat is not in error, as I had been wondering.

But it still does not explain why Thomas and Maria apparently had no (surviving) children from 1806 to 1815.
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