Avenue House is a Grade II listed Victorian mansion. The history of the house goes back centuries with the land on which the house sits granted to the Knights Templars in 1243, from which the old name for the land, Temple Croft Fields, originates.
From 1312 the land belonged to the Knights Hospitallers until their estates were seized by Henry VIII in 1540. The land then passed through various hands until 1732 when it was bought by Thomas Allen, whose family were Lords of the manor of Finchley, who built the existing manor. A relative of the Allen family, Rev. Edward Cooper, built a villa on the site in 1859. This house later became known as Avenue House. The house takes its name from The Avenue which runs behind the house, and was originally the route between Bibbesworth Manor and the church of St Mary’s Finchley.
In 1874 Avenue house was bought by the famous ink manufacturer Henry Charles Stephens. During Stephens' residency, he purchased the adjoining ten-acre Temple Croft Field and the gardens were laid out, to designs by Robert Marnock. The house and grounds were left to the 'people of Finchley' in trust with the Finchley Urban District Council (UDC) by Stephens in his will in 1918, with a condition that they always be open for the use and enjoyment of the public, subject to reasonable regulation.
Due to need after the first World War, the estate was used between 1919 and 1925 by the RAF as a military hospital before the grounds were eventually opened to the public in May 1928. The house was used for many years as a public library and as the offices of Finchley Borough Council after Council Offices in nearby Hendon Lane were destroyed by enemy action in the Second World War. The basement was used as an air-raid shelter.
In 1989 the building was gutted by fire, but refurbished to retain its character and updated to provide modern and comfortable facilities for conferences, exhibitions and functions for businesses and families, particularly weddings.
In 2002 a charity, Avenue House Estate Trust, took over the management of the estate from the London Borough of Barnet. In 2014 the estate became Stephens House and Gardens to better interpret the history of the house and its facilities.