Colonial Office Telegram Code East Africa WWI

[colinalsbury]

Looking at the Colonial Office papers relating to the King's African Rifles in East Africa in 1918, where my maternal grandfather was attached as CSM to 3rd Regiment, I find that the code used in telegrams is not any version of the A B C electronic telegraph code that I can find but has a very similar style. Does anyone know what the code used was and whether any code books survive?

Sample code words include:

REASONJOKE = Recruiting Officers

EAGLESTONE = East Africa

APTISTA = 1st August

WEDGESHY = 4

OUTBRAGGED = by order of

There are plenty of decoded telegrams in the Colonial Office files downloadable but it would be handy to have access to a full surviving code book if one exists

Thanks