Uniqueness and nonexistence of some graphs related to $M_{22}$

There is a unique distance regular graph with intersection array i (7, 6, 4, 4; 1, 1, 1, 6); it has 330 vertices, and its automorphism groupM 22.2 acts distance transitively. It does not have an antipodal 2-cover, but it has a unique antipodal 3-cover, and this latter graph has automorphism group 3.M 22.2 acting distance transitively. As a side result we show uniqueness of the strongly regular graph with parameters (v, k, , ) = (231, 30, 9, 3) under the assumption that it is a gamma space with lines of size 3.