The text on the brass plate (which is approx. 50 cm / 1.6 ft x 30 cm / 1 ft) reads :
Orate pro anima
CHRISTOPHER SEROCOLD TENNANT
2nd Lieut. Welsh Guards, of Cadoxton, Neath, Wales.
Born 1897. Fell in action 3rd Sept. 1917 near Langemarck. Aged 19
Ex voto matre sua
Sancta Teresia a Jesu Infante pro nobis
This officer, so I found, was killed in a minor operation, two weeks after the Battle of Langemark (8 km / 5 miles eastward). That same day (3 Sept.), and the following day 16 other ranks fell in the same battalion (1st Welsh Guards).
He is the son of Charles Coombe and Winifred Coombe Tennant, of Neath, Wales. His biography was written in 1918 already by Sir Oliver Lodge ("Christopher - A Study in Human Personality"). I do not possess that biography, but it is in the Ypres In Flanders Fields Documentation Centre. It is obvious that I want to read it as soon as I can.
As to the rediscovery I can only conjecture what must have happened, based on what some people in Elverdinge told me, and also having found that George Christopher Serocold Tennant (CWGC) or George Christian Serocold Tennant (SDGW) was buried at Canada Farm cemetery (Elverdinge, near the road to Poperinge).