19439 is listed under "Vehicles for Disposal", with a note that the reason is "Fire damage" in the most recent fleet allocation card which I have seen.

As the card is dated for November last year, it's quite possible that events have moved on and the vehicle disposed of - but it won't be coming back!

With regard to the suggestion that older vehicles have been repaired: Bodywork damage can be relatively easily sorted, sometimes by cannibalising parts of other vehicles; in many cases it can be largely cosmetic, although damage around the chassis may have an effect on the structural integrity of the vehicle which would make a significant difference to the outcome. A fire, on the other hand, will result in major damage to the parts of the bus that make it go, as well as to the lower portions of the body, which would be an altogether different approach to possible repair and far more likely resulting in disposal for scrap once re-usable parts have been stripped.