An accurate variational upper bound to the nonrelativistic clamped nucleus energy of the beryllium atom in the 2(1)P state is computed from a 1200-term exponentially correlated Gaussian wavefunction with a Cartesian prefactor. New integrals necessary to evaluate matrix elements are presented. Test calculations were performed on 2(1)P helium and 2(1)P lithium atoms yielding energies which are, respectively, 1 nanohartree and 0.35 microhartree in error. The upper bound to the energy of 2(1)P beryllium amounts to -14.473442016 hartree and the energy extrapolated to the basis set limit is -14.473458(5) hartree. The effect of the finite nuclear mass on the total and excitation energies is also assessed. The predicted excitation energy is 0.193947(7) hartree (42566(2) cm(-1)) in perfect agreement with the experiment.