Soren Andreasen, a social scientist at Dalberg Global Development Partners who supervised the writing of the report, defended it, saying that it was clear that the numbers were rough estimates.

Thomas' roundhouse is located on the fictional Island of Sodor, which the Rev. Awdry dreamed up in the early 1950s, after visiting the Isle of Man to preach at a Sunday school festival.

Drexel asked two of their brightest students, Joe Woodland and Bernard Silver, to find a solution.