Part of this is slightly off topic, but anyadvice woul be useful.

I'm researching my father's cousin who was commissioned into 3 HLI in
World War 1.

I've seen and read his officer's record in the National Archives.

This is where we go off topic.

He was mentioned in dispatches in 1918. He was (as he was for all his
active service) seconded to the King's African Rifles and involved in
the East African Campaign. I've found the listing of his "mention" in
the appropriate edition of the London Gazette.

However none of us knows what his "mention" was for. It's not in his
officer's record (Although his service medal record is.).

He served with 3/4 KAR, and 4 KAR seems to be the only WW1 battalion
for which no regimental history was written.

For those who don't know, this is even more confusing as the KAR were
the responsibility of the Colonial Office, not the War Office.

I've read Van Deventer's actual dispatch about the relevant part of
the campaign and he doesn't say why he's giving any of the mentions.

There are a lot of files in the Archives which cover the KAR in
general which I will try. But am not too hopeful.

Can anyone think of any other source where I might find out what
the "mention" was for?

Roger.