(20 Oct 2015, 2:02 pm)Dan wrote Lothian Buses show "Route Diverted" on the destination display (as below), and also have other variations such as "Part Route":
Rugby Specials 885 and 853 by Stuart Montgomery, on Flickr
Lothian Buses 309 SN09CUC Gyle Centre by Bruce Kitchener, on Flickr
So it's a similar system, but I believe theirs is manual rather than automatic.
Is that like the picture of 9119 you showed us?