As pointed out by Rosie Bevan, CP states that Agnes, daughter of John, and sister of Payn and Eustace FitzJohn, m. Roger de Valognes and was a widow in 1185. CP suggests she was aged 50 or 60 and more in 1185 (Rosie would have her much older, which I think is correct). Rosie Bevan may also be thinking that Agnes was daughter of Eustace and Beatrice de Vescy, as the dates (especially if Agnes were b. 1110/15) would work well.