Here is information on his SOE Personnel file at Kew: Marcel LECCIA, aka Georges LOUIS, aka BAUDOUIN, aka LABOURER - born 01.01.1911 | The National Archives
I did find this interesting Booker was luckier than Leccia. Buchenwald's communist underground managed to smuggle out word of the presence of Allied airmen in the camp and the German air force, the Luftwaffe, was made aware of this. The Luftwaffe - which had an interest in ensuring that captured airmen were treated in accordance with the Geneva Convention - petitioned for them to be moved. Soon they were transferred, as official prisoners of war, to Stalag Luft III in Poland- the setting for the 1963 film, The Great Escape. Booker was then sent to another PoW camp near Berlin, where he was held captive by the Red Army before being freed. Booker
Just to tidy this thread up a bit. Here is some information on the intended recipient of the engagement ring, who as mentioned was an SOE agent herself: Odette Wilen Search results: odette wilen | The National Archives Search results: odette strugo | The National Archives
How a ring tells the story of a forgotten secret agent Leccia was 33, from a distinguished Corsican Resistance family, and his experiences of war had left him with good cause to be distrustful - he'd ended up in Buchenwald after he was betrayed by a supposed comrade who was secretly working for the Germans. TD