On 2^nd Febraury 1920 William St. John Fremantle was created 1^st Earl of Midleton and among those he entertained at Peper Harow were Lord Curzon, Balfour and Churchilll. 

After the Earl's death in 1942, his two sons were killed within days of one another in 1943 during the Italian campaign, and the estate finally passed out of the hands of the Midleton family.

The Canadian Army requisitioned the estate for their headquarters in the latter years of the War and many thousands of Canadian troops were billeted in the surrounding areas of south-west Surrey.

An auction was held in 1944 which dispersed the assets of the estate.  Somerset Farm and Oxenford Grange were sold to their tenant farmers and many cottages and plots in the neighbouring villages of Shackleford and Eashing were purchased by local residents.

In the post-War years, Peper Harow House and its estate buildings came under the ownership of a charitable trust which cared for young people with troubled backgrounds.  This work became world-renowned and proved highly successful in the long-term residential care of these children.  Today the estate is primarily residential with some crop and livestock farming continuing at Home Farm.