The ancient elm known as Bag's or Bagg's Tree grew, until 1975, on the Downs above Harwell, between the Chilton track and the Winnaway. It gave its name to the surrounding field, and is mentioned in the John Loder charity as some fourteen acres awarded in lieu of Grove land in the West Field of Harwell, at the time of the enclosures (1802 - 05). It is still owned by the Harwell Parochial Charities.
Traditionally it is said to have marked the spot where Bagrun, king of the Danes, died of wounds on his way back to the Thames at Goring after being defeated by Alfred at the battle of Ashdown. A succession of trees was probably planted over the centuries to mark the site. When the latest elm had to be felled, its trunk measured 4.3 metres round. Its age was estimated at about 275 - 300 years, roughly the life span of an elm.
Between 1695 and 1722, twelve people called Baggs are mentioned in the parish register as having been baptised or buried. The Oxford Dictionary gives the verb bag(g) as meaning cut (wheat etc.) with reaping-hook, originating in the seventeenth century; also badge, a verb with the same meaning, of unknown origin.