Henry inherited his titles after the execution of his elder
          brother Thomas by Edward II. He joined Edward II's queen, Isabella of
          France, and Roger Mortimer when they invaded England in September 1326
          and he captured Edward II at Neath Abbey in Wales.
              He was Edward's gaoler at Kenilworth until, in 1327, the king was
          moved to Berkeley Castle and subsequently murdered. Henry then became
          the guardian of the young Edward III. In 1329 he began plotting
          against Roger Mortimer, but was discovered. Henry went blind in 1330,
          but was still able to help Edward III plan the successful overthrow of
          Mortimer that year.

Source: Leo van de Pas