In this Letter we present triple differential cross sections for equal energy sharing kinematics for double photoionization of the helium atom at 20 and 40 eV above threshold in the framework of the hyperspherical partial wave theory. This supplements our earlier work [J. Phys. B: At. Mol. Opt. Phys. 36 (2003) 2707] in which we were successful in showing fully, gauge independence of the results in our formalism. Also in this Letter we treat cases in which the Stokes parameter S1 < 1 so that partial polarization of the photon source is also taken into account. Agreement in shape with the convergent close coupling [A.S. Kheifets, 2003, private communication; H. Bräuning, et al., J. Phys. B: At. Mol. Opt. Phys. 31 (1998) 5149] calculation and the experiments appears to be excellent. © 2003 Elsevier B.V. All rights reserved.