Sounds like BS to me. Escorted into French airspace? That would mean the French had to be lurking on the boundary of their UIR just on the offchance that a BA flight should come along and doesn't make contact with the French after an incorrect/nil handover with London ATC. Seems an unlikely scenario to me. There are occasional intercepts of BA aircraft over French, but there are occasional intercepts of many airlines aircraft over France. Nothing wrong with the flight, just the French airforce practicing.