In 1310 he not only inherited his father's lands in Norfolk, Suffolk, Wiltshire and Hampshire but was himself summoned by King Edward II for military service against Scotland.
In 1326, Ingham was appointed Seneschal of Gascony, the highest post in what remained in English possession, holding extensive powers over the law and finance of the duchy.
However he was pardoned on 8 December 1330, the new king acknowledging his loyal service in the past, and his property was restored to him with the important exception of grants from the crown.
On 29 June 1331 he was reappointed as seneschal in Aquitaine, responsible for the peace, order, and defence of the duchy at a time of deteriorating Anglo-French relations, which culminated in the outbreak of the Hundred Years' War in 1337.
The defences of the duchy had been undermined by the loss of several key castles in the previous war and the loyalty of the local nobility was divided, as many owned estates on both sides of the border.
By August 1336 the duchy was on a war footing again, Ingham being ordered to forbid all Gascon men-at-arms to leave the land without licence and to ensure all major strongholds were properly garrisoned, equipped, and victualled.
Overall English strategy concentrated on attacking the north of France, with the result that Ingham in the south-west received neither troops nor funds from England and had to rely entirely on local resources.
The income of the duchy depended mainly on tolls and custom dues from goods conveyed along the great rivers, but trade dried up almost entirely with the onset of war.
[2] His widow died on 11 October 1350 and was buried beside him,[3][4] the inscription, in medieval French, having been recorded as: Mounsier Oliver de Ingham gist icy et Dame Elizabeth sa compagne que luy Dieux de les almes eit mercy (Sir Oliver Ingham lies here and Dame Elizabeth his wife; may God have mercy on their souls).