Why did Edward III oppose the Treaty of Northampton with Scotland?

Edward III opposed the Treaty of Northampton because he viewed the concession of Scotland’s independence as a source of deep personal and political resentment.1

The treaty was signed in 1328 during the early years of his reign, while he was still under the guardianship of his mother, Isabella of France, and her lover, Roger Mortimer. Although Edward was forced to sign the settlement under their pressure, he remained dissatisfied with the loss of English influence over the Scottish realm.1

As he matured and asserted his own authority—eventually executing Mortimer in 1330—Edward sought to restore England to the powerful status it held under his grandfather, Edward I. He viewed the treaty as a degrading concession and actively looked for opportunities to reverse it, eventually taking advantage of the death of Robert I and the youth of his successor, David II, to reassert English interests in Scotland.1