The identity of Elizabeth’s maiden name is, unfortunately, not 100% conclusive.  The circumstantial evidence trail is as follows:

 

Against being a Daubeney:

 

St-Lo2 (20K)
  1. The transcription  of George Daubeney’s will (proved 1690) held by the National Archives mentions a Jane Plowman and an Elizabeth St Lo.
  2. The 18th (& 19th?) edition(s) of Burke’s LandedSt-Lo3 Gentry notes the marriage details of the daughters of George Daubeney of Gorwell - Jane Daubeney married William Plowman Clerk* and Elizabeth Daubeney married Thomas St Lo. However, this may well be based upon the content of George Daubeney's will above. 
    (*The online records at the IGI imply that Clerk was a surname rather than an occupation.  The chances are that a comma was missed or overlooked between “Plowman” and “Clerk”.)

 

For being a Daubeney;

 

St-Lo (53K)
  1. The Dorset Record Office have details of the marriage at Abbotsbury on 26th May 1686 of "Thomas Saintler Clark" and a "Jane Daubney". (The marriage may well have been performed by William Plowman who was the Vicar of Abbotsbury.) 
  2. The Harleian Society’s Visitations of Dorset 1677 record that Thomas St Lo, the Rector of Pulham, married Jane, daughter of George Daubeney. They had four sons; John, Robert, Thomas & Lawrence 
  3. There is a baptism record at Winterborne Steepleton for a John St Loe dated 26th July 1688 with the parents given as Thomas and Jane St Loe.  (A John St Lo is listed as the eldest child in The Harleian Society’s Visitations of Dorset 1677)
  4. George Daubeney’s will mentions his grandchildren; Dawbeny Plowman, Anne Plowman, John St Loe, George Dawbeny, Anne Dawbeny and Elizabeth Dawbeny.
  5. William Plowman’s wife is recorded as Elizabeth in the baptism records of Winterborne Steepleton - Ann, William, John, George and Elizabeth.
  6. The first two children born to William at Abbotsbury were George and Daubeney.  Daubeney Plowman was baptised at Gorwell – the seat of George Daubeney.  (There is no mention of the mother’s name.)
  7. A George Daubeney (brother?) witnessed Elizabeth’s will.  (The only children mentioned in her will were those born after leaving Abbotsbury.) 
  8. Her nephew, Lawrence Saintlo, is a beneficiary and trustee in Elizabeth’s will. 
  9. That Elizabeth came from a family of some substance is deduced from the fact that she was in a position to leave the impropriate parsonage on Tincleton church to her son the Rev John Plowman.

 

The balance of probability is that Elizabeth was a Daubeney. On that basis, Eliazbeth’s pedigree would be:

 

1)      Eystein Glunold of Romsdal in Norway,.

2)      Malahulc or Tresney, the Uncle of Rollo, Duke of Normandy (876-917).

3)      Richard, vice comes of the Cotentin, joint Lord of the Channel Islands, who founded the Chapel of St Sauveur le Vicomte and was living 933.

4)      Unidentified grandson.

5)      Niel, Lord of the Channel Islands and vice comes of the Cotentin.

6)      NIEL, who succeeded to his father's fief and office in 1040.

7)      William, and settled at Aubigny in Brittany.

8)      William of Dol, in Brittany, Butler to KING WILLIAM I, acquired lands in England after the Conquest, held Stockthorne and Belvoir jure uxoris.

9)      Roger of Ivry, Butler to KING WILLIAM I in Normandy and Castellan of Rouen.

10)  WILLIAM LE MESCHIN, who held half Stock-horn and Tallington as held by his grandfather.

11)  RALPH DE ALBINI, succeeded to South Petherton, was a Crusader and bore gules four fusils in fesse argent; m 1182, Sybil, dau of Piers de Valoins, and d while on Crusade at the siege of Acre 1190.

12)  Ralph, of Ingleby, Lincs;

13)  RALPH D'AUBENEY, 4th of South Petherton, 3rd of Ingleby.

14)  ELIS DAUBENEY, 6th of South Petherton, and of Ingleby, Seigneur de Laudal, did homage for his bro's lands 26 Aug 1294, served in Wales 1294, summoned to Parliament by Writs from 24 June, 1295 to 25 Jan 1304-5 as Lord Daubeney.

15)  SIR RALPH DAUBENEY, 7th of South Petherton, did homage for his father's lands 21 June, 1326.

16)  SIR GILES DAUBENEY, 8th of South Petherton, and of Ingleby.

17)  SIR GILES DAUBENEY, 9th of South Petherton and of Ingleby.

18)  SIR GILES DAUBENEY, 11th of South Petherton, did homage for his bro's lands 22 Nov 1416.

19)  WILLIAM DAUBENEY, 12th of South Petherton, who had livery of his father's lands 19 Feb 1445-46.

20)  JAMES DAUBENEY, High Sheriff of Dorset 1488.

21)  GILES DAUBENEY, of Wayford, Somerset.

22)  JOHN DAUBENEY, of Wayford, and of Gorwell, Dorset.

23)  GEORGE DAUBENEY, of Gorwell.

24)  HENRY DAUBENEY, of Gorwell, Dorset.

25)  GEORGE DAUBENEY of Winterbourne Steepleton, Dorset.

26)  Elizabeth Daubeney.