I got Agnes' parents from Fred Lathrop, World Connect db=flathrop, rootsweb.com. Fred referred to a source "Abell, p. 28". The marriage by Gilbert to a daughter of Somerled is a little unusual to say the least. The dates are agreeable and the name "de Lisle/ of the Isles" would tend to support it, but the chances of a Lord from Suffolk running coming into contact with a daughter of Somerled seem remote. ##check ancestry
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Curt Hofemann, curt_hofemann@@yahoo.com, provided additional info & insights in the following post-em:
most secondary sources list her as: Agnes d'Lisle
Fred referred to a source "Abell, p. 28".
"Medieval English Ancestors of Robert Abell" written & self published by Carl Boyer III, 2001, P.O. Box 220333, Santa Clarita, CA 91322-0333, printed by Sheridan Books, ISBN: 0-936124-22-9. It's $35 + $4 shipping directy from the author.
I am skeptical that her father was Somerled. All sources Iíve seen state Agnesí parentage is unknown. There are listings on WorldConnect that show her parents as Alan of Galloway & Helen díLisle, but that is clearly chronologically impossible.
For Somerled check "The Scots Peerage", edited by Sir James Balfour Paul, multiple volumes published 1904-1914.
Regards,
Curt