Tacitus writes that, by insisting that legionary legates who had not so far held the praetorship should immediately proceed to that office, Asinius Gallus ‘altius penetrare et arcana imperii temptari’. In C.Q. N.S. xvi (1966), 327, I suggested that this demand of Gallus’ was probably probing dangerously deeply into and perhaps threatening to wreck the carefully worked-out imperial promotions system, the working of which has been examined by Birley.

It is the purpose of this note to look at a number of examples of such irregularity, which, though not as early as the debate during the course of which Gallus made his suggestion, do at least illustrate the process later in the Julio-Claudian era.