From CWGC

Rank: Serjeant
Service No: 11159
Date of Death: 17/03/1920
Regiment/Service: Royal Garrison Artillery 121st Heavy Bty.
Awards: M M
Grave Reference: S.11.
Cemetery: MITCHAM (CHURCH ROAD) BURIAL GROUND

Forenames from Ancestry:

Ancestry.com. British Army WWI Service Records, 1914-1920 [database on-line]. Provo, UT, USA: Ancestry.com Operations Inc, 2008.
Original data: The National Archives of the UK (TNA): Public Record Office (PRO).

He died in the Mitcham Military Hospital (the Holborn Union Workhouse on Western Road) and his name is on the memorial.

From CWGC

Rank: Corporal
Service No: 46129
Date of Death: 30/03/1917
Regiment/Service: Northamptonshire Regiment 1st Labour Coy
Grave Reference: W. 12.
Cemetery: MITCHAM (CHURCH ROAD) BURIAL GROUND
Additional Information: Husband of Hester Beryl Lewis of 18 Craven Hill Gardens, London.

From Ancestry :

Frank Ball Lewis in the UK, Soldiers Died in the Great War, 1914-1919

Name: Frank Ball Lewis
Birth Place: Stoke Newington, Middlesex
Death Date: 30 Mar 1917
Death Place: Home
Enlistment Place: Newcastle, Northumberland
Rank: Corporal
Regiment: Northamptonshire Regiment
Battalion: Infantry Labour Companies. 8th Company
Regimental Number: 46129
Type of Casualty: Died
Theatre of War: Home
Comments: Formerly 4660, K.R.R.C