A convergent series solution based on the theory of elasticity is presented for bending of a sandwich plate strip with an isotropic homogeneous core and composite orthotropic facesheets with variable fibre volume fraction in the in-plane direction. The accuracy of first-order shear deformation theory is assessed against this benchmark solution. Further, it is shown that the benefit of using functionally graded material facesheets depends critically on the span-to-thickness ratio of the plate.