The same spring, on 12 May 1787, the still hesitant Wilberforce held a conversation with William Pitt and the future Prime Minister William Grenville as they sat under a large oak tree on Pitt's estate in Kent. Under what came to be known as the "Wilberforce Oak" at Holwood House, Pitt challenged his friend: "Wilberforce, why don't you give notice of a motion on the subject of the Slave Trade? You have already taken great pains to collect evidence, and are therefore fully entitled to the credit which doing so will ensure you. Do not lose time, or the ground will be occupied by another." Wilberforce's response is not recorded, but he later declared in old age that he could "distinctly remember the very knoll on which I was sitting near Pitt and Grenville" where he made his decision.