I would not expect a vast number of French firms to recruit at Oxbridge schools - there are several reasons for this. Linguistically, they are fishing in a reduced pond of talent that would work. They have alternatives near to home in the form of HEC and INSEAD.
That doesn't mean to say that as an Oxbridge MBA you cannot make a career in France work. I am sure firms would be receptive to hearing from you, and your profile may well be more exciting than people going to HEC or INSEAD. What it does is put the onus on you, rather than serving to bring you those opportunities unchallenged.
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