I just had an interesting idea--what if we could add DCC/sound to the TTTE line?  Each DCC decoder/sound card will come equipped with each engine's distinctive whistle sound and appropriate chuff sounds (low-pitched for Gordon, high-pitched for Percy, for example).  Maybe, if possible, we could equip the card with a few lines of dialogue from Ringo Starr (or whoever is narrating now---I forget) in lieu of the "Bell" function (bells are only used on US locomotives BTW). 

DCC won't skyrocket the price THAT much, but it goes well beyond the expectations of the fans, considering that the series was originally made in 1984, before DCC ever existed!