Cornwall enjoyed a brief but active career.
It was probably during his term as escheator that Otto made a respectable marriage. His wife was the daughter of one of the leading families of Hereford and widow of a Gloucestershire esquire, Robert Mattesdon, who, through his mother, was coheir of the Herefordshire knight, Sir John Chandos† (d.1428), and of Thomas Berkeley† (d.1405) of Coberley (Gloucestershire). Mattesdon had not been as wealthy as such kinship might be taken to imply, for Chandos had alienated most of his lands from his heirs. None the less, the widow enjoyed dower in the manors of Stoke Orchard, Coberley and Kingsholm (Gloucestershire), together with a jointure interest in the Chandos moiety of the manor of Lugwardine (Herefordshire).
On 13 Oct. 1459 Cornwall accompanied his brother Thomas to the election held at Hereford on the day after the Yorkists had ignominiously fled from nearby Ludford Bridge when outfaced by a superior Lancastrian force. It is likely that the brothers had been with the latter, and they now did further service for Henry VI’s cause by helping to ensure the return of two local royalists, their uncle, Sir John Barre, and Thomas Fitzharry*. A few weeks later, on 5 Nov., Otto Cornwall was himself returned for Hereford. It is not known whether he had property in the city, but he had obvious recommendations for election: his wife was a Chippenham, a family with a distinguished recent record of parliamentary service for Hereford, and both this family and his own were supporters of Lancaster. If the electors needed any further encouragement, it might have lain in the consideration that the mayor who conducted the hustings was his wife’s first cousin, John Chippenham.
Cornwall’s commitment to Lancaster certainly went beyond a mere willingness to serve in a controversial Parliament. Since he was exempted from the pardon of 6 Mar. 1461, issued at the beginning of Edward IV’s reign, he was almost certainly in arms against the Yorkists at one or more engagements of the civil war of 1459-61, almost certainly Ludford Bridge and probably also at the battle of Mortimer’s Cross, not far from Hereford, early in February 1461. In contrast with his eldest brother, Thomas, however, he was not considered irreconcilable, and he quickly won a pardon. Indeed, on 11 Dec. 1461 he was not only pardoned but restored to his manor of Brimfield and the lands he held in his wife’s right. A few months later, on 29 Apr. 1462, he sued out a further pardon under the designation ‘gentleman, alias of Hereford, esquire, alias late escheator of Herefordshire’.
