Howick Hall is not open to the public at the moment, but there are long term plans to restore the ground floor and to open it with an exhibition on the family, the Great Reform Bill of 1832, the garden and arboretum, and local natural history. This will take time.
The Hall was built in 1782 by a Newcastle architect, William Newton. The entrance was originally on the south side. Charles 2nd Earl Grey employed George Wyatt in 1809 to enlarge it by moving the entrance to the north side, filling out the front hall and the two quadrants linking the house to its wings, and building the first terrace on the south side, presumably all to accommodate his ever increasing family.
A big fire destroyed the whole of the interior of the main house in 1926, with all the contents of the top two floors; it was rebuilt in 1928 to quite different designs by Sir Herbert Baker, who altered the north façade by introducing a portico above the front hall in order to make the house smaller with an open well in the middle, with a rotunda linking the front and back on the ground floor. Disciples of Georgian architecture are not amused.
The family moved out shortly after the death of 5th Earl Grey, and in 1973 the present Lord Howick converted the West Wing into the family home, where they now live.