That's a shame. Three of the original cast members gone between series 3 and 4. I hope it continues to be worth watching - series 3 was, IMO, one of the most consistently entertaining programmes I've ever seen, and most of that had more to do, IMO, with the wonderfully ludicrous concepts than with the cast per se (I mean, it helped that they were good, but any lineup of good actors would have been equally enjoyable), but even so, it's going to be strange going into series 4 with only one of the original characters left...
OTOH, Being Human managed it...
