Many thanks. I think the death you have for a Mornington King in Buckinghamshire could well be him. By the way the father was baptised Evan William King in Longhope but on his army record and on the marriage registration he was William Evan King - this confused me for ages!

http://www.forum.forest-of-dean.net/index.php?id=36604

KING Evan William
KING WILLIAMS
1888 Gloucester Gloucester, Huntley 17 408

Year: 1889
Month: Jan
Day: 27
Parents_Surname: KING
Child_Forenames: Evan William
Fathers_Forenames: Henry
Mothers_Forenames: Lucy
Mothers_Surname:
Residence: Longhope
Occupation: Labourer
Officiating_Minister: A.Ledward Curate
Event: Baptism
Memoranda:
Notes:
Register_Reference:
Page_Number: 118
Parish_Chapel: Longhope

Living at 21 Henry St Bargoed in 1915 with wife Ellen Gladys

Name: William Evan King
Estimated Birth Year: abt 1889
Age at enlistment: 26
Document Year: 1915
Regimental Number: 3744
Regiment Name: Royal Garrison Artillery

Name: Evan W King
Birth Date: abt 1889
Date of Registration: Apr-May-Jun 1945
Age at Death: 56
Registration district: Bedwellty
Inferred County: Monmouthshire
Volume: 11a
Page: 104

This is an unusual name so I wonder if anyone has come across it? His birth was registered 1923 in Merthyr Tydfil - but I think he lived in the FOD, at least temporarily in the 1930s, with elder brother Leslie W and father Evan William King.

Name: Ellen G Hayward
Spouse : William E King
Date of Registration: Jan-Feb-Mar 1915
Registration district: Merthyr Tydfil
Inferred County: Glamorgan
Volume Number: 11a
Page Number: 1119

siblings:-
James H King Jan-Feb-Mar 1917 Merthyr Tydfil Monmouthshire
Leslie W King Apr-May-Jun 1919 Merthyr Tydfil Wales
Evelyn M King Apr-May-Jun 1921 Merthyr Tydfil Wales

Name: Morrington G King
Mother's Maiden Surname: Hayward
Date of Registration: Apr-May-Jun 1923
Registration district: Merthyr Tydfil
Inferred County: Wales
Volume Number: 11a
Page Number: 1411

Name: Mornington King
Birth Date: 27 Jan 1923
Date of Registration: Oct 1987
Age at Death: 64
Registration district: Chiltern and Beaconsfield
Inferred County: Buckinghamshire
Volume: 19
Page: 1136

and possibly another one ..

Name: Mornington Carson King
Birth Date: 24 Oct 1900
Date of Registration: Jul-Aug-Sep 1974
Age at Death: 73
Registration district: Barrow-in-Furness
Inferred County: Lancashire, Cumbria
Volume: 1
Page: 0077

1911 10 Lanover, Row, Pontnewynydd
Walter Kings 42
Emma Kings 41
Francis Kings 14
Mornington Kings 11
Irene Kings 6
Amy Kings 10
Walter Kings 4

1900
Walter King abt 1871 Tunbridge Wells, Kent, England Head Abersychan, Monmouthshire
Emma King rabt 1872 Varteg, Monmouthshire, Wales Wife Abersychan, Monmouthshire
Kawa M King abt 1898 Garss, Monmouthshire, Wales Daughter Abersychan, Monmouthshire
Warrington K King abt 1900 Garss, Monmouthshire, Wales Sergeant Abersychan, Monmouthshire

1891
Walt F King abt 1869 Tunbridge, Kent, England Member of Crew (Member) Royal Navy, Hampshire