▁about ▁ ▁south ▁of ▁H empt on , ▁is ▁Il bury ▁Iron ▁Age ▁hill ▁fort , ▁at op ▁a ▁hill ▁ ▁high . ▁Near ▁the ▁fort ▁is ▁the ▁site ▁of ▁a ▁desert ed ▁medieval ▁village , ▁also ▁called ▁Il bury . ▁In ▁ 1 9 8 0 ▁the ▁village ▁site ▁was ▁redis cover ed ▁and ▁Med ieval ▁pot tery ▁from ▁the ▁ 1 2 th , ▁ 1 3 th ▁and ▁ 1 4 th ▁centuries ▁was ▁found . ▁ ▁Top onym , ▁man or ▁and ▁castle ▁ ▁The ▁to pon ym ▁is ▁derived ▁from ▁the ▁Old ▁English ▁for ▁" place ▁of ▁the ▁people ▁of ▁D æ da ". ▁" D æ da " ▁was ▁short ▁for ▁Ang lo - S ax on ▁names ▁such ▁as ▁D æ dh ē ah . ▁The ▁to pon ym ▁was ▁sp elt ▁D ad int one ▁around ▁AD ▁ 9 5 0 , ▁D æ d int un ▁around ▁ 1 0 5 0 ▁and ▁D ad inton ▁in ▁ 1 1 9 0 . ▁ ▁After ▁the ▁Norman ▁con quest ▁of ▁England ▁in ▁ 1 0 6 6 , ▁William ▁the ▁Con quer or ' s ▁step - bro ther ▁O do , ▁Bishop ▁of ▁Bay e ux , ▁held ▁the ▁man or ▁of ▁D ed d ington . ▁O do ▁had ▁the ▁outer ▁ba iley ▁of ▁D ed d ington ▁Castle ▁built ▁in ▁what ▁is ▁now ▁the ▁east ▁of ▁the ▁town . ▁The ▁inner ▁ba iley ▁on ▁the ▁east ▁side ▁of ▁the ▁castle ▁seems