Hi Caroline,
I did wonder that as Edith died in a Coleford nursing home she may have been buried in one of the FoD council cemeteries/crematoria, probably the nearest at Mile End ?
However searching their site doesn't find Edith (or Jimmy, Walter, or Charles) either there or at Yew Tree Brake nr Cinderford, see

http://www.forestofdean.gov.uk/nqcontent.cfm?a_id=6707&tt=graphic&externalurl=w...

(Note, this site's search engine doesnt like too much detail !, best to just enter the surname and read thro all the findings. This site carries records back to the late 50s which should therefore include your ancestors' records if they're there).

This does of course leave many Church cemeteries in the Forest. Given that Walter is buried at Christchurch, and this is near Coleford wrt Edith, that may be your best starting place.
This site carries Memorial Inscriptions for Christchurch, The search engine does finds one Cook, Harold who died in 1975 aged 56.
Sorry I don't know how much later than this the Cemetery was/is? being used, or how complete this survey is ?.
http://www.forest-of-dean.net/?Memorial_Inscriptions_Christchurch

If you don't know, this recent prior thread will help locate the Church & navigate the Cemetery.
http://www.forum.forest-of-dean.net/index.php?id=38108
http://www.forum.forest-of-dean.net/index.php?id=18039

I cannot find any other Council Cemeteries in the Lydney area(by internet searching Chepstow & Monmouth) but am not certain of this, I'm sure other users will know..

It's relatively easy to browsing this site's Burial Records for all Griffiths and then Cook buried within Church cemeteries between say 1959 and 1999, by entering date as 1979 +/- 20 years. As expected this gives several hits, there are understandably some in the Lydney area ie Lydney, Alvington, Woolaston etc; it's probably worth you browsing these yourself to see if you can spot possible clues in the names & dates ?.
I wondered if this could this be your Charles Cook, but it appears not as the next PR IS a closer match and the dates/ages clash ?

Record_ID: 240765
Entry_Number: 292
Year: 1963
Month: Jan
Day: 21
Surname: COOK
Forenames: Charles
Residence: Woolaston Common
Age_at_death: 89
Officiating_Minister: WLR Gould Rector
Event: Burial
Cause_of_death:
Memoranda:
Notes:
Register_Reference: P12 IN 1/14
Page_No: 37
Parish_Chapel: Alvington
Soundex: C200

So it looked to me like this is your Charles, you've probably already found this Baptism, I think this is the ONLY Charles Stuart/Stewart Cook(e) on this site's database (UPDATE, BUT! no this is a different one, presumably a relative, see below.....)

Record_ID: 2660
Entry_Number: 589
Year: 1902
Month: Jan
Day: 19
Parents_Surname: COOKE
Child_Forenames: Charles Stewart
Fathers_Forenames: Ebenezer
Mothers_Forenames: Edith Kate
Mothers_Surname:
Residence: Brockweir
Occupation: Packer
Officiating_Minister: Lionel Ford Priest-in-Charge
Event: Baptism
Memoranda:
Notes:
Register_Reference: P12 IN 1/5
Page_Number: 74
Parish_Chapel: Alvington
Soundex: C200

Do you have any clues at all as to when he died, please ?. I've tried searching FreeBMD and GlosBMD for his future PRs but without success, too many to choose from.

Also from this site his siblings:
1890 COOKE Ada Mary, Ebenezer & Edith Kate, Pentre Labourer Alvington
1893 COOKE Percy George, Ebenezer & Edith Kate, Pentre South Wales Foundryman Alvington
1899 COOKE Norah Winifred Annie, Ebenezer & Edith Kate, Woolaston, Labourer, Alvington
1902 COOKE Charles Stewart, Ebenezer & Edith Kate, Brockweir, Packer, Alvington
1904 COOKE Jessie Gwenith, Ebenezer & Edith Kate, Brockweir, Packer, Alvington
1907 COOKE Edith Charlotte, Ebenezer & Edith Kate, Alvington, Packer, Alvington
1909 COOK Amy Josephine, Ebenezer & Edith Kate, Alvington, Packer, Alvington
1911 COOKE James Edward, Ebenezer & Edith Kate, Alvington, Platelayer, Alvington

After a surprising struggle I find them on the 1911 Wales Census c/o the current free access, so they are still in the Forest at 2 Spring Row Alvington Nr Lydney Glos altho an older family member is presumably still in London:

Name Relation to Head Birth Date Age Gender Marital Status Occupation Birth City Birth County Birth Country Address
Ebenezer Cooke, Head abt 1866 45 Male Married 22 yrs Railway Platelayer Alvington Gloucestershire England
Edith Kate Cooke, Wife abt 1870 41 Female Married 22yrs Woolaston Gloucestershire England
Percy George Cooke, Son abt 1893 18 Male Single Beaterman At Leather Board Factory Ystradyfodwg Glamorgan Wales
William John Cooke, Son abt 1894 17 Male Single Machine Boy At Leather Board Factory Ystradyfodwg Glamorgan Wales
Norah Winnefred Amme Cooke, Daughter abt 1899 12 Female School Woolaston Gloucestershire England
Charles Stuart Cooke, Son abt 1902 9 Male St Briavels Gloucestershire England
Jessie Gwyneth Cooke, Daughter abt 1904 7 Female St Briavels Gloucestershire England
Edith Charlotte Cooke, Daughter abt 1906 5 Female Woolaston Gloucestershire England
Amy Josephine Cooke, Daughter abt 1909 2 Female Alvington Gloucestershire England
James Edward Cooke, Son abt 1911 3/12 Male Alvington Gloucestershire England
Grace Gladys Cooke, Granddaughter abt 1909 2 Female London St Pancras

I hope this helps and wish you well with your search.

Well done MPG, you found him, must admit I was surprised I couldnt even find him on the 1911 Census without tracing the rest of the family - as your post suggests he's a difficult chap to find, blooming electrickery eh ?!, I trust this sites PRs over the rest anyday of course. THANKS !!

That said given his early passing this clearly is NOT the same Charles that Caroline recalls....
This family certainly got around a bit, altho not uncommon in those days especially given their living near the Severn river & railway towards South Wales.
Thought I recognised the unforgettable name Ystradyfodwg, I studied in that area at Pontypridd at the old Mining College in the 1980s, lived in Porth for one of those years. This site shows the dramatic population increase typical of the Taff/Rhondda area when coal became King. Not too far from Llanelli too of course.
http://en.wikipedia.org/wiki/Ystradyfodwg

I think its this brother and sister

Name: Charles S Cooke
Mother's Maiden Surname: Cox
Date of Registration: Apr-May-Jun 1924
Registration district: Monmouth
Inferred County: Wales
Volume Number: 11a
Page Number: 30

Name: Rita J Cooke
Mother's Maiden Surname: Cox
Date of Registration: Jul-Aug-Sep 1928
Registration district: Monmouth
Inferred County: Wales
Volume Number: 11a
Page Number: 29

Parents

Name: Walter E Cooke
Spouse :Edith E Cox
Date of Registration: Jan-Feb-Mar 1923
Registration district: Llanelly
Inferred County: Carmarthenshire
Volume Number: 11a
Page Number: 1747

which leads us neatly back to
Name: Edith Ethel Cox
Date of Registration: Jul-Aug-Sep 1894
Registration district: Monmouth
Inferred County: Monmouthshire
Volume: 11a
Page: 23

1911 Yorkley Slade West Dean Nr Lydeny, Gloucestershire, England
Albert Cox 48
Elizabeth Cox 50
George Lambert Cox 20
Charles Mayard Cox 19
Cora Annie Cox 15
Hilda Cox 13
Albert Edward Cox 9
Lenoard Cox 6

1901
Albert Cox abt 1863 Yorkley Slade, Gloucestershire, England Head West Dean, Monmouthshire
Elizabeth Cox abt 1862 Yorkley, Gloucestershire, England Wife West Dean, Monmouthshire
George L Cox abt 1891 Yorkley Slade, Gloucestershire, England Son West Dean, Monmouthshire
Charles M Cox abt 1893 Yorkley Slade, Gloucestershire, England Son West Dean, Monmouthshire
Edith E Cox abt 1895 Yorkley Slade, Gloucestershire, England Daughter West Dean, Monmouthshire
Corah A Cox abt 1897 Yorkley Slade, Gloucestershire, England Daughter West Dean, Monmouthshire
Hilda Cox abt 1898 Yorkley Slade, Gloucestershire, England Daughter West Dean, Monmouthshire
Gilbert W Cox abt 1900 Yorkley Slade, Gloucestershire, England Son West Dean, Monmouthshire

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Ἀριστοτέλης A Gloster Boy in the Forest of Dean ><((((*>