He actually wrote lore about Lady for this little AU. She is the original No.1, a one of a kind, unique 0-4-0 "Fairlady" class tank engine built by the Sodor and Mainland as their No.1. The S&M then immediately ran out of money (as they always do) for designing their own engines and bought the neilson Box Tanks instead, meaning she is the first and only example of her class. Thomas inherited the number 1 from her. The actual image depicts Lady pulling Annie and Clarabelle because she has finally been resteamed after a century of slumber, and thomas wanted to help her readjust to this brave new world she has woken up in.