Little is known of the layout of the original estate but since 1957 Howletts has been a wild animal park established by John Aspinall with the intention of breeding and protecting rare and endangered specimens and returning to the wild. The park has a successful Black Rhino breeding programme. The park also has the largest herd of African Elephants in the UK along with a host of other animals including Bison, Sumatran Tigers, Iberian Wolves, Clouded Leopards, Gorillas to name but a few.

Howletts is primarily a landscaped Zoo Park, with some concentrated shrub planting in regions around the animal enclosures. The area of formal gardens is small, being centred around and within the walled gardens, and consists of a variety of formal bedding plants (dahlias, cannas, geraniums etc) and roses. An area has been retained for fruit and vegetables, and the Victorian lean-to greenhouses are in good repair and used to grow vines, nectarines and peaches. An elegant lean-to stove-house (maintained at 40°C) produces banana fruits. The associated farm also produces animal fodder, and some of the woodland is coppiced to provide woody herbage for them.

The park is ancient, imparked it is said in the 15th or 16th century when the manor was owned by Sir Henry Palmer. It then covered 120 hectares. Some of the present very ancient and massive trees, especially sweet chestnuts and oaks, could date from this period. The elegant classical house was built around 1797 and is a fine focal point, with a very impressive Ionic portico on the south side, and a Victorian arboretum (planted about 1860 by a Mr Gipps) around the house. Mr Aspinall purchased the neglected house and remaining 22 hectares in the 1950s as a site suitable for keeping and breeding a wide assortment of the world's endangered animals.

In the 1987 storm, approximately 1,000 trees were lost at Howletts and Port Lympne (also a Zoo park owned by Mr Aspinall), and both were subsequently closed to the public for six months for damage work. At Howletts, the larger parkland trees lost included oaks, Huntingdon elms, and some cedars, including one especially large cedar of Lebanon. A replanting has been undertaken. The lime avenue south of the house has lost two trees, but a large gingko remains, and the massive ancient ‘Howletts chestnut' survives with the loss of one limb.

Site timeline
1957: The estate was bought by John Aspinall and turned into a wild animal park

1987: In the 1987 storm, approximately 1,000 trees were lost at Howletts and Port Lympne (also a Zoo park owned by Mr Aspinall), and both were subsequently closed to the public for six months for damage work.