149th Brigade Trench Mortar Battery war diary - May 1918

[Manipled Mutineer]

Dear all, I am drawing something of a blank. Does anyone know if a war diary exists for the light trench mortar batteries of 149th Brigade, 50th Division for the month of May 1918? I seem to only be able to find a diary for May-August 1916. I would be keen to get wind of a diary as I am researching a man who went missing whilst attached to the 149th Bde LTMB ('last heard of 15 May 1918') and who I think was captured during the Battle of the Aisne 1918. I have read the 149th Bde war diary for the month but it's not terribly illuminating for my query (not that there is any particular reason why it should be). 

Many thanks, Anthony