Great Plane of Mottisfont

The largest London plane in Britain, by Wikipedia's account, grows beside a house that began as a medieval priory. Mottisfont, in the Test valley near Romsey, was founded as an Augustinian priory in the early 13th century and turned into a country house after Henry VIII dissolved the monasteries. The plane came much later, though nobody can yet say exactly when. It has a name of its own, the Great Plane of Mottisfont, and OpenStreetMap's mappers tag it as a landmark about 30 metres tall. Tree recorders have reported a bigger height, a vast girth and an 18th-century planting, and they may well be right, but those figures are still unconfirmed reports. Its age is an open question. If you know where the measured record lives, tell us. The superlative, too, is worth holding loosely until a register entry backs it. What nobody disputes is the tree itself, a single crown big enough to have earned a proper name on a map, standing close to the house that grew out of the priory. Mottisfont belongs to the National Trust and charges admission, free to members. The nearest station is Dunbridge, about 1.5 kilometres away, and from Winchester it is a day out rather than a quick hop, with a change of train on the way.