We suggest that the unique X-ray source 1E161348-5055 at the centre of the supernova remnant RCW 103 consists of a neutron star in close orbit with a low mass main sequence star . The time signature of 6.67 { \ > hr } is interpreted as the neutron star ’ s spin period . This requires the neutron star to be endowed with a high surface magnetic field of \sim 10 ^ { 15 } { \ > G } . Magnetic or/and material ( propeller ) torques are able to spin rapidly the young neutron star down to an asymptotic , equilibrium spin period in close synchronism with the orbital period , similarly to what happens in the Polar Cataclysmic Variables . 1E161348-5055 could be the first case of a magnetar born in a young low mass binary system .