57. Where the judge advocate accepts a plea of guilty to any charge, the judge advocate may (with the Director's consent) order that any other charge—
(a)to which the defendant has not pleaded,
(b)to which the defendant has pleaded not guilty, or
(c)as respects which the judge advocate has recorded a plea of not guilty under rule 56(5),
is to lie on the file, not to be proceeded with without the leave of the court or the Appeal Court.