Of course Tilly was herding sheep. That’s what Border Collies do. :=)
My Dad had a border collie when he herded sheep in the high desert as a boy. Said they were the smartest breed ever created. Mom and the kids went in to buy him one for his 70th birthday. The dog and a pet hen were his favorite companions until the day he died (second only to Mom or the kids and grandchildren when we were able to visit).