In the end I looked it up myself (which I could have done at the start, but I thought there might be someone who had personal information). Lorraine Squadron was in fact 342 Sqd formed in 1943 with Bostons, and then onto Mitchells in 1944, disbanding in 1945 when the crews reverted back to the French Air Force.
I still did not find any stories about Romain Gary, but from various sources was informed he was "Polish", or "Russian" (which he was not) and also a Navigator (which he was not). Just shows you.
Laurence