Seeing these unusual pictures taken inside North Lincolnshire's only railway tunnel by someone at Network Rail immediately reminded Brigg Blog of a very likeable book written a good few years ago by Stephen Gay.
We still have a copy of Through Kirton Tunnel, featuring all the stations on the iconic Brigg line between Sheffield and Cleethorpes, with impressive pictures and informative text.
The former station master's house was still standing on Brigg station at the time, together with the late Victorian footbridge.
We recall seeing Stephen and his trusty dog Thunder on the footbridge one Saturday morning. Perhaps they took the train from Sheffield to undertake some research.
In view of the number of changes made along the line since the book was printed, we would love to see an updated version.
Our thanks go to photographer Rob and to Paul Johnson, of The Friends of the Brigg Line for forwarding the images to us.