The Park encloses 400 acres and has large herds of both red and fallow deer. Every year the stags grow antlers which they shed in the spring and, as they mature, the antlers grow to huge proportions. The deer have been in the Park for many centuries - the earliest mention of them is in 1660. In the archives there are reports of the Mound being used by the Helmingham Volunteers to practise their musketry during the Napoleonic Wars, but the Monument itself was constructed in about 1860, from the bricks of an ornamental seventeenth-century walled arboretum on the site, which had fallen into disrepair.

John Constable, whose brother was steward of the Tollemache woodlands, lived for some time at Helmingham Rectory, and painted a number of versions of A Dell in Helmingham Park. The oak tree in that picture, with its singular curved trunk, still stands. Some of the famous Helmingham oaks in the Park are estimated to be up to 900 years old, and many have immense girths, but the splendid oak avenue leading up the front drive was planted about 1680. This avenue and many trees in the Park suffered terribly in the great storm of 1987; a large replanting scheme is being carried out so that future generations will see little change.