Radeng, if he comes off the plane, which was his intention in the first place, the local immigration authorities would have to accept him. They would of course have to technically refuse him entry on the grounds he could not satisfactorily provide evidence of his identity and nationality. The British Embassy consular section would then become involved given that he is almost certainly a British national, especially where there is a minor, so the captain would be absolved of his responsibility. But this all costs money and more disconcertingly, the Consular staff would have to provide assistance when there could be other British nationals in a greater need of the assistance of the embassy.