George William Campbell, 6th Duke of Argyll GCH, PC (22 September 1768 – 22 October 1839), styled Earl of Campbell from 1768 to 1770 and Marquess of Lorne from 1770 to 1806, was a Scottish Whig politician and nobleman.
I could find little about his work during the Regency but he’s listed as being part of Priny’s Set. So it could very well be that he did very little worth noting until his friend became king. But I did find one mention that he was a Counciler to the Prince of Wales from 1812-1820.
George Campbell, 6th Duke of Argyll – Wikipedia
The London GazettePublication date: 13 September 1833 Issue: 19084 Page: 1675
CAMPBELL, George William, Mq. of Lorne (1768-1839), of Inveraray Castle, Argyll. – History of Parliament Online