The following information was supplied in a post-em by Curt Hofemann, curt_hofemann@@yahoo.com:
aka: Guillaume de 'Simplex' de Blois, Seigneur de Sully
simplex = simple (minded). Burke's Peerage 1919 p24 says he was "an imbecile".
Count of Chartres, j.u. Sire de Sully [Ref: Paget p10]
Lord of Salejo, Sire De Sully [Ref: Moriarty, Turton] (I think "Sire" should be "Seigneur" & unable to locate "Salejo" which looks Spanish, not French. Also, in French is there a differentiation of Lord vs Sire?... Curt)
brother of King Stephen [Ref: CP V:155]
died before 1150 [Ref: ES II:46, ES III:110]
Regards,
Curt