We present time–resolved spectroscopy and photometry of the double–lined eclipsing cataclysmic variable V347 Pup ( = LB 1800 ) . There is evidence of irradiation on the inner hemisphere of the secondary star , which we correct for using a model to give a secondary star radial velocity of K _ { R } = 198 \pm 5 km s ^ { -1 } . The rotational velocity of the secondary star in V347 Pup is found to be v \sin i = 131 \pm 5 km s ^ { -1 } and the system inclination is i = 84.0 ^ { \circ } \pm 2.3 ^ { \circ } . From these parameters we obtain masses of M _ { 1 } = 0.63 \pm 0.04 M _ { \odot } for the white dwarf primary and M _ { 2 } = 0.52 \pm 0.06 M _ { \odot } for the M0.5V secondary star , giving a mass ratio of q = 0.83 \pm 0.05 . On the basis of the component masses , and the spectral type and radius of the secondary star in V347 Pup , we find tentative evidence for an evolved companion . V347 Pup shows many of the characteristics of the SW Sex stars , exhibiting single–peaked emission lines , high–velocity S–wave components and phase–offsets in the radial velocity curve . We find spiral arms in the accretion disc of V347 Pup and measure the disc radius to be close to the maximum allowed in a pressureless disc .