Reginald was involved in the process that led to the peaceful ascension of Henry fitzEmpress to the throne of England in 1154 and served the new king as a royal justice afterwards.
[1] While William was on crusade, Reginald granted the right to form a merchant guild to the inhabitants of Lewes, as long as his brother agreed after his return.
Reginald continued in his role as an administrator under the new Earl, eventually becoming his main advisor, and also began to serve the King, signing several royal charters as a witness.
[9] In 1164 he was present at the Council of Clarendon,[1] which was part of the long struggle between Henry and the new Archbishop of Canterbury, Thomas Becket, over control of the English church.
[1] Reginald was one of the four main justices involved with the general eyre[a] between 1168 and 1170, along with Richard of Ilchester, Guy the Dean of Waltham Holy Cross, and William Basset.
[12][b] Besides these administrative and judicial roles, Reginald was a baron of the exchequer in 1169 and held the office of sheriff of Sussex from 1170 to 1176,[1] and was a member of the King's Council, or curia regis, in 1170.
This group, led by Gervase of Cornhill, complained that the archbishop was sowing dissension in the land by his excommunication of Roger of York and the two bishops, but Becket managed to calm the officials by stating he would consider the matter and reply to them the next day.
At the meeting the following day the group was joined by several clergymen sent by the excommunicated ecclesiastics, but nothing was accomplished beyond further offers by Becket to consider alternative options.
[17] In 1173 Reginald worked for the King, along with Richard fitzNigel and Nicholas de Sigillo, to assess a land tax on parts of the royal estate.
[19] Although his considerable debts (including the levy for the Wormegay Barony) had been tacitly ignored while he was in the king's service, as soon as he retired the Exchequer demanded that he start to quickly repay them.