Regular orbits of symmetric and alternating groups

Given a nite group G and a faithful irreducible FG-module V where F has prime order, does G have a regular orbit on V ? This problem is equivalent to determining which primitive permutation groups of ane type have a base of size 2. In this paper, we classify the pairs (G;V ) for which G has a regular orbit on V where G is a covering group of a symmetric or alternating group and V is a faithful irreducible FG-module such that the order of F is prime and divides the order of G.