The Railway series
books 27 - 42
The Fat Controller needs a new engine to help out on the Branch Lines, and knows where to get one, but first - he needs to trial one similar!
Wilbert soon finds himself filling in for Percy on Thomas's Branch Line and encountering all sorts of eventualities that Sodor engines are known for during his visit!
Thomas is invited to the National Railway Museum in York, and hits a level crossing gate and receives a parking ticket on the way!
Despite every eventuality, Thomas ends up helping Green Arrow when they encounter trouble on a Rail Tour, and receives Honourary Membership of the National Collection.