Misty Island Rescue
Thomas wasn’t saying that diesels couldn’t be useful, Diesel said that he’s a really useful engine too and he said no Diesel I’m sure Sir Topham Hatt means a really useful steamie you’ll never be that, if he was saying that only steamies could be useful he would’ve just said steamie and left the really useful part out,when he said you’ll never be that,yeah it’s a little prejudice but he doesn’t think that diesels are completely useless even though he has a superiority complex towards them, he literally was having a friendly interaction with Salty before Diesel came and I’m pretty sure the not useful part was just because of Diesel’s personality, I’m pretty sure he wouldn’t have said any of this to Salty or Mavis, and if he really hated diesels that much he wouldn’t have saved Diesel from falling off the cliff.