the answer is - probably- there is a Mary who fits the bill in 1851 with a son William.

Year 1816
Month May
Day 12
Parents Surname EDWARDS
Child Forename(s) William
Father's Forename(s) Richard
Mother's Forename(s) Mary
Mother's Surname
Place of Residence Hundred of St Briavels
Occupation Labourer
Officiating Minister Henry Prowse Jones
Event type Baptism
Memoranda
Notes
Register Reference P110 IN 1/5
Page No 16
Parish/Chapel Littledean

Month Feb
Day 27
Surname EDWARDS
Forename(s) Richard
Place of Residence Little Dean Hill
Age at death 80 years
Officiating Minister J.Chell
Event Burial
Cause of death
Memoranda
Notes
Register Reference P109 IN 1/11
Page No 52
Parish/Chapel Drybrook

1841 Littledean Hill
Mary Edwards abt 1782 Gloucestershire, England Dean Forest Gloucestershire
Mary Edwards abt 1820 Gloucestershire, England Dean Forest Gloucestershire
Mary Edwards abt 1839 Gloucestershire, England Dean Forest Gloucestershire

Year 1844
Month Sep
Day 21

Groom Surname LUCAS
Groom Forename(s) George
Groom Age at Marriage Of Full Age
Groom condition Batchelor
Groom Rank or Profession Collier
Groom Residence Township of East Dean
Groom Father's Surname Lucas
Groom Father's Forename(s) Richard
Groom Father's Rank or Profession Black Smith

Bride Surname EDWARDS
Bride Forename(s) Mary
Bride Age at Marriage Of Full Age
Bride Condition Spinster
Bride Rank or Profession [not stated]
Bride Residence Township of East Dean
Bride Father's Surname Edwards
Bride Father's Forename(s) Richard
Bride Father's Rank or Profession Labourer

Licence or Banns Banns
Date of banns [not stated]
Signature or Mark They Both Mark
Witness 1 Mark of William Hewlett
Witness 2 Mark of Elizabeth Hewlett
Other witnesses
Officiating Minister Thomas May.Wetherell
Event type Marriage
Memoranda
Transcriber's Notes
Register Reference P354 IN 1/7
Page No 42
Parish/Chapel Westbury

Year 1847
Month Mar
Day 24
Surname LUCAS
Forename(s) George
Place of Residence East Dean
Age at death 29
Officiating Minister Henry M Willis
Event Burial
Cause of death
Memoranda
Notes
Register Reference P110 IN 1/12
Page No 8
Parish/Chapel Littledean

Year 1847
Month Dec
Day 25

Groom Surname HALE
Groom Forename(s) James
Groom Age at Marriage Full Age
Groom condition Bachelor
Groom Rank or Profession Labourer
Groom Residence Dean's Hill
Groom Father's Surname Hale
Groom Father's Forename(s) James
Groom Father's Rank or Profession Nailer

Bride Surname LUCAS
Bride Forename(s) Mary
Bride Age at Marriage Full Age
Bride Condition Spinster
Bride Rank or Profession
Bride Residence Dean's Hill
Bride Father's Surname Edwards
Bride Father's Forename(s) Richard
Bride Father's Rank or Profession Labourer

Licence or Banns Banns
Date of banns
Signature or Mark Both mark
Witness 1 Frederic Rowe
Witness 2 Caroline Trigg
Other witnesses
Officiating Minister T. G. Smythies
Event type Marriage
Memoranda
Transcriber's Notes
Register Reference P85/1 IN 1/4
Page No 18
Parish/Chapel Cinderford St Johns

1851
James Hale abt 1817 Flasby, Gloucestershire, England Head East Dean Gloucestershire
Mary Hale abt 1821 Little Dean, Gloucestershire, England Wife East Dean Gloucestershire
Jenicey Hale abt 1849 Little Dean, Gloucestershire, England Daughter East Dean Gloucestershire
William Hale abt 1845 Little Dean, Gloucestershire, England Son East Dean Gloucestershire
Mary Edwards abt 1839 Little Dean, Gloucestershire, England Daughter East Dean Gloucestershire

1851 Littledean Hill
William Edwards abt 1816 Littledean; Hill, Gloucestershire, England Head Extraparochial Gloucestershire
Mary Edwards abt 1782 Kent,[WEST?] England Mother Extraparochial Gloucestershire

1861 Littledean Hill
Mary Edwards abt 1782 Westbury, Gloucestershire, England Head Flaxby, Littledean and Newnham Gloucestershire
William Edwards abt 1816 Sea [LEA] Hamblet, Gloucestershire, England Son Flaxby, Littledean and Newnham Gloucestershire

not sure where the parents are in 1871 - travelling ? -

Name: Mary Meredith Edwards
Name: Anthony Thomas Roberts
Year of Registration: 1861
Quarter of Registration: Apr-May-Jun
District: Westbury On Severn
County: Gloucestershire
Volume: 6a
Page: 369

Name: Mercilla Roberts
Year of Registration: 1864
Quarter of Registration: Jul-Aug-Sep
District: Westbury On Severn
County: Gloucestershire
Volume: 6a
Page: 203

Year 1864
Month Aug
Day 7
Parents Surname ROBERTS
Child Forename(s) Mereilla
Father's Forename(s) Anthony Thomas
Mother's Forename(s) Mary
Mother's Surname
Place of Residence East Dean
Occupation Labourer
Officiating Minister J. Davies
Event type Baptism
Memoranda
Notes
Register Reference P1 IN 1/8
Page No 15
Parish/Chapel Abenhall

Year 1869
Month Jun
Day 3
Parents Surname ROBERTS
Child Forename(s) Thomas
Father's Forename(s) Anthony Thomas
Mother's Forename(s) Mary
Mother's Surname
Place of Residence East Dean
Occupation Miner
Officiating Minister John Senior
Event type Baptism
Memoranda
Notes
Register Reference P1 IN 1/8
Page No 28
Parish/Chapel Abenhall

1871
James Hale abt 1817 Cinderford, Gloucestershire, England Head East Dean Gloucestershire
Mary Hale abt 1820 Cinderford, Gloucestershire, England Wife East Dean Gloucestershire
Noah Hale abt 1856 East Dean, Gloucestershire, England Son East Dean Gloucestershire
Merietta Robert abt 1865 East Dean, Gloucestershire, England Grandchild East Dean Gloucestershire

1871
Thomas Roberts abt 1870 East Dean, Gloucestershire, England Pauper Westbury On Severn Gloucestershire

1881
Anthony Roberts abt 1838 Eastdean, Gloucestershire, England Head Westbury On Severn - East Dean Gloucestershire
Mary Roberts abt 1838 Eastdean, Gloucestershire, England Wife Westbury On Severn - East Dean Gloucestershire
Annie Roberts abt 1880 Eastdean, Gloucestershire, England Daughter Westbury On Severn - East Dean Gloucestershire
Dinah Roberts abt 1875 Eastdean, Gloucestershire, England Daughter Westbury On Severn - East Dean Gloucestershire
James Roberts abt 1877 Eastdean, Gloucestershire, England Son Westbury On Severn - East Dean Gloucestershire
Joice Roberts abt 1876 Eastdean, Gloucestershire, England Daughter Westbury On Severn - East Dean Gloucestershire
Marcella Roberts abt 1865 Eastdean, Gloucestershire, England Daughter Westbury On Severn - East Dean Gloucestershire
Mary J. Roberts abt 1872 Eastdean, Gloucestershire, England Daughter Westbury On Severn - East Dean Gloucestershire
Thomas Roberts abt 1871 Eastdean, Gloucestershire, England Son Westbury On Severn - East Dean Gloucestershire
Mary Roberts abt 1843 Eastdean, Gloucestershire, England Boarder Westbury On Severn - East Dean Gloucestershire

Year 1881
Month Apr
Day 15
Surname ROBERTS
Forename(s) Mercilla
Place of Residence The Plump
Age at death 17
Officiating Minister William Barker Vicar
Event Burial
Cause of death [not sta
Memoranda Name is annotated OY Anthony Letter P in left hand margin
Notes
Register Reference P109 IN 1/12
Page No 148
Parish/Chapel Drybrook

1891
Anthoney Roberts abt 1838 Flaxley, Gloucestershire, England Head East Dean Gloucestershire
Mary Roberts abt 1839 Little Dean, Gloucestershire, England Wife East Dean Gloucestershire
Annie Roberts abt 1880 East Dean, Gloucestershire, England Daughter East Dean Gloucestershire
Charlotte Roberts abt 1882 East Dean, Gloucestershire, England Daughter East Dean Gloucestershire
James Roberts abt 1877 East Dean, Gloucestershire, England Son East Dean Gloucestershire

Thank you Slowhands for all the info, it looks like the Mary c1782 you found in the 1851 census with her son is the right family.Though her being listed as originating from Kent is a bit odd.

From the transcribed parish records and the 1841 census on here William Edwards marries a Belinda Jones in 1839 (who dies in 1848) he then marries again in 1871 I think as both show his father as Richard Edwards

Could you tell me if he his still single on the 1861 census, then that would be the right line I think

Regards Sue