The production cross-sections for protons, antiprotons and kaons in proton-proton collisions at centre-of-mass energies s =30.6 and 52.8 GeV at large angles and for the transverse momentum range p T<1.2 GeV/ c for protons and antiprotons and 0.2< p T<0.5 GeV/ c for kaons have been measured. The charged particle composition is given in the range 0.2< p T<0.5 GeV/ c and show that the K ± and p ± components have doubled over this p T-range. The ratio of positive to negative produced particles increases with p T.