Mr Ward built the Fountain Inn and a new stone wharf in 1813 . He started rebuilding St Mary's Church where he, his wife Mary and six of their children are buried. The vicarage built at the same time is now a nursing home for the elderly. By 1815 the Round House, a toll house was built and let to the Highways Commissioners it was used for the collection of road taxes until 1889. Debourne Lodge and the Round House on maps of the period however neither building is part of the current estate although they still exist. Also by 1817 The Park wall which is approximately six feet in high and built by master builder Henry Brading was completed.
George Ward died in 1829 and the estate was inherited by his son, George Henry Ward. He had extensive property holdings in the Cowes area and was known locally as King Ward. George Henry Ward (1784-1849) married Mary Saunders (1773-1838) his cousin, daughter of William Saunders M.D., Physician to the Prince Regent. They had no children. He built a pier from the wharf at the Fountain Inn and made further additions to the family house. In the year 1837 Northwood House was reconstructed and redeveloped. The eastern and northern elevations are similar to those of the previous house. A western wing and an entrance pavilion on the north side opening onto a forecourt with a side wall of classical design concealing the stable block were new additions. The modern Ward Avenue formed the boundary between the pleasure gardens and the park. The kitchen garden was where the Park Court flats now stand. An old wall and a fig tree survive.
In 1849 George Henry Ward died and the estate is inherited by his nephew, William George Ward. From 1852 to 1863 Northwood House and grounds were leased out to Robert White Esq and he operated a school from Egypt House and leased land from Northwood Park as playing fields. In 1882 William George Ward died and the estate was inherited by his son Edmund Granville Ward.
A group of Benedictine nuns who were exiled by France lived in Northwood House from 1902 until 1906. In the First World War 1914 to 1918 Northwood House was used as a Red Cross Hospital. Edmund Granville Ward died in 1915 and his brother Wilfred inherited the estate he subsequently died in 1916. His son Captain Herbert Joseph Ward inherited the estate.
Herbert Joseph Ward gifted the estate in 1929 to Cowes Urban District Council and it stated that the ground was for use as a pleasure garden for the people of Cowes and the house as municipal offices. In September 1929 HRH Princess Beatrice Royal Governor of the Isle of Wight and youngest daughter of Queen Victoria accepted the deed to Northwood House and grounds from Captain Herbert Ward. The Princess handed the deeds over to Mr F W Beken, chairman of Cowes Urban District Council. In the 1930's Tennis Courts were build on the park grounds.
From the early 1970's Medina Borough Council took over from Cowes Urban District Council and in 1978 Northwood House Charitable Trust was registered wth the Charity Commission and Isle of Wight Council succeeded Medina Borough Council after several changes to the trust and a small amount of renovation work and the registery office move to Northwood House the Council relinquished its beneficial rights and withdrew its support leaving the trustees to manage the estate. In 2012 Northwood House Charitable Trust Company Limited was established.