This is the grave of Sarah Morgan.  Unfortunately we can only read a small amount of the weather eroded inscription, but we could see the name Sarah and a death date so looked in the burials list (which is available to view inside the church).

The burials register has a few details about Sarah.  It states she was 65 years in the Service of the M. of Ailesbury.  She was resident in Savernake Forest House at the time of her death and she was buried on 22nd March 1872 aged 97 years.  The ceremony was taken by J. L. Kingsbury, vicar of Easton Royal, Som., Chaplain to the Marquis of Ailesbury, J. D. Hodgson, vicar of Great Bedwyn, and Edward Slater Browne (who was the vicar of Savernake Forest at that time).