  We report on the design and first tests of a device allowing for measurement
of ultracold neutrons polarisation by means of the simultaneous analysis of the
two spin components. The device was developed in the framework of the neutron
electric dipole moment experiment at the Paul Scherrer Institute. Individual
parts and the entire newly built system have been characterised with ultracold
neutrons. The gain in statistical sensitivity obtained with the simultaneous
spin analyser is $(18.2\pm6.1)\%$ relative to the former sequential analyser
under nominal running conditions.
