That the unit is qualified of "de Vendée" does not imply that it was the single one.

Perhaps the "record" of 8th was known by capt Morris, due to the large publicity made to atrocities in Vendée in british press?

In France, the most pictured Westermann's hussars are the Hussars of Death / Black Hussars, for symbolic reason. But they staid in Vendée until 1796.