Has Moussa Koussa really defected? There are some indications that this may be a diplomatic mission -- negotiating an exit strategy for the Gaddafi regime -- rather than a defection.
1. Moussa is not accompanied by his family, who are apparently still in Libya. If he had been planning defection he would have had no difficulty in getting them out of the country before he flew to London.
2. He was accompanied to Tunisia (but not beyond) for his flight from Djerba to Farnborough by Abdel Ati al-Obeidi who remains a trusted counsellor of Gaddafi (and a trusted intermediary in the eyes of the UK and the USA).
3. If Moussa had defected, he would surely have negotiated immunity from prosecution for any personal involvement in Lockerbie (if Libya was implicated in any capacity, Moussa would inevitably have been personally involved). According to Foreign Secretary William Hague, no such immunity has been granted. This suggests that his visit is already covered by diplomatic immunity.