The death certificate of a child would probably have the father's name and occupation on it.
In the occupation column it usually says son/daughter of .....
There seems to be no birth reg of Robert (bap 26 Sep 1840, Takeley, as Potters - from Family Search)
Similarly, Ellen, if she is another child of your Sophia (bap 3 July 1842, Takeley, Potters)?
The next three baptisms at Takeley on FS
James Vollers, 6 April 1843 (perhaps that may be Volters?)
William Volters, 2 April 1845
Thomas Walters, 9 Sep 1848
There is a birth of a Thomas Walters, registered Sep 1848, Dunmow
Added to the death reg of Robert Walters in 1840, I am wondering if other possible birth regs of Sophia's children may also be as Walters - hence my asking about James, March 1843, and William, March 1845, in Dunmow.
There are only those four BMD entries for the name Walters in Dunmow district at that time.
John
EDIT But if Sophia's husband was no longer around, and Robert and the others appear to be illegitmate, you would be unlikely to see Mr Valters name on Robert's death certificate.