In 1795 his mother's first cousin, Arthur Blayney of Gregynog, Montgomeryshire, who had always been expected to leave his property to Thomas (his godson), died, bequeathing all his heritage to Lord Tracy, a stranger in blood; and this was a great disappointment to Bates and his family.

[3] He now threw himself with "quadrupled energy into an agricultural career," and on attaining his majority became tenant of his father's small estate of Wark Eals, on North Tyne.

"[3] He speedily achieved renown as a breeder of taste and judgment, and at Charles Colling's famous Ketton sale in 1810 he bought for 185 guineas a cow called Duchess, which was the foundress of a well-known tribe of shorthorns.

A year later he made a great sensation at the first show of the then newly established English Agricultural Society, held at Oxford in 1839, with his tour shorthorns, all of which won the prizes, and one of which, called "Duke of Northumberland", was said to be "one of the finest bulls ever bred.

[3] Up to 1849 he had enjoyed robust health, living almost in the open air, and very simply; but a painful disease of the kidneys carried him off on 25 July 1849 at the age of seventy-four.

An appreciative obituary in the Farmers' Magazine speaks of his liberality and hospitality, and describes his litigiousness as "but a nice and discriminating view of public duty": Convince his judgment or appeal to his feelings, and he was gentle and yielding; but once rouse his opposition, and he was as untiring in his warfare as he was staunch and unflinching in his character ...

He wrote a vast number of letters to the newspapers, mainly on the politics of agriculture ... His writing was terse and forcible, and he had a remarkable tact in making facts bear upon his propositions, as well as a wonderful readiness in calculation and mental arithmetic.