coronation street execs have ditched a ban on talent doing voiceover work .
former star katy cavanagh had been ticked off for doing bbc iplayer ad .
show 's other actors staged a ` mutiny ' , forcing ban to be overturned .
other actors who 've cashed in include benedict cumberbatch -lrb- pedigree -rrb- , olivia colman -lrb- andrex -rrb- , shane richie -lrb- plenty kitchen roll -rrb- .