War Gratuity

Unlike the service gratuity the war gratuity paid a amount based on both the rank of the man and the length of service (home and/or overseas) – up to a maximum of 60 months service between 4th August 1914 and 3rd August 1919.
Private
Service with overseas service
£5 for the first 12 months service then 10s per month
Service without overseas service (minimum service period of 6 months to qualify)
£5 for the first 12 months service then 5s per month
Corporal
Service with overseas service
£6 for the first 12 months service then 10s per month
Service without overseas service (minimum service period of 6 months to qualify)
£6 for the first 12 months service then 5s per month
Serjeant
Service with overseas service
£8 for the first 12 months service then 10s per month
Service without overseas service (minimum service period of 6 months to qualify)
£8 for the first 12 months service then 5s per month
Colour or Staff Serjeant
Service with overseas service
£10 for the first 12 months service then 10s per month
Service without overseas service (minimum service period of 6 months to qualify)
£10 for the first 12 months service then 5s per month
WO 2
Service with overseas service
£12 for the first 12 months service then 10s per month
Service without overseas service (minimum service period of 6 months to qualify)
£12 for the first 12 months service then 5s per month
WO 1
Service with overseas service
£15 for the first 12 months service then 10s per month
Service without overseas service (minimum service period of 6 months to qualify)
£15 for the first 12 months service then 5s per month

Source: https://wargratuity.wordpress.com/2015/08/16/how-much-was-the-war-gratuity/