This appears to be either a copy of the 1767 Basire print (PAH3294) omitting the shipping, or of the original drawing in the Gough Collection of the Bodleian (assuming that has no shipping). The title information in the cartouche is wrong inasmuch as Placentia was rebuilt, or at least extended, from Humphrey of Gloucester's much smaller manor house of Bellacourt by Edward IV and his successors after Humphrey's death in 1447, and totally rebuilt by Henry VII around 1500. The drawing's style could predate Basire but might also be a deliberate attempt to produce an 'antiquarian effect' by someone working thereafter into the early 19th century, though probably not much after 1800.