After his foreclosure on Deuchar, Marshall formed a new Glengallan parnership with William Ball Slade before returning to England where he died shortly afterwards. An eminent and respected figure, W.B. Slade distinguished himself, over the next 34 years, as a pastoralist, philanthropist and active Anglican.

The homestead block, sold to the Gillespies in 1904, came back into Slade hands after the untimely death of Alex Gillespie in 1927. The new owner, Oswald Slade, having bequeathed his property to the Chruch of England, in 1949 gifted the stone house for demolition and re-erection at Slade School as War Memorial classrooms. Fortunately for Glengallan, neither plan eventuated. The imposing Glengallana Gates and pillars were moved to Leslie Park in Warwick in 1940.

In 1972, the Church sold the property to the Smith Family Partnership. The stone house, long derelict, remained empty. In 1993, the newly formed Glengallan Homestead Trust Ltd was able to acquire the Homestead precinct for one-third the market value with the Smith family proviso that the place be kept in the public interest. Thus began the lengthy restoration project which was finally enabled by a Federal Government Centenary of Federation grant through the Queensland Heritage Trails Network. The heritage-tourism operation opened to the public on Australia Day 2002 and continues under the Board of Directors of Glengallan Homestead Trust with a team of dedicated volunteers.