A study has been made of the propagation of solar cosmic rays after their release from a flare under the assumption of diffusive motion around the sun and in interplanetary space (where &kgr;1 is taken to be 0). For two-dimensional diffusion around the sun and for a diffusion coefficient &kgr;11(r) =&kgr;0r&bgr; in interplanetary space, approximate analytic solutions have been found for the density N(t) and the anisotropy &xgr; (t). Both density and anisotropy are found to be prolonged at 1 AU relative to those for impulsive injection. By combining these, the diffusion coefficients at the sun and at 1 AU can be extracted separately. To check the approximate analytic solution, numerical computation over a wide range of propagation conditions indicates that mean free paths derived near 1 AU are accurate to within 13% (when they are fitted up to time of maximum, tm) or to within 25% (up to 2tm). The effect of one- or three-dimensional diffusion around the sun instead of two-dimensional diffusion is to change the derived mean free path by less than 25% (up to tm). The effect of a non-negligible loss (or escape) of particles at the sun has been evaluated; for all except the largest value of loss rate suggested, the error is small up to tm. Application of the solution to the ground level event of September 1, 1971, when the flare was ?40¿ behind the west limb, gives a solar diffusion coefficient &kgr;s/rs2=1.5 h-1 and a mean free path at 1 AU of 0.15 AU for the case &bgr;=0.