My guess would be that the normal locos hired out for driver route training are pretty much booked up as the freight paths to Scunthorpe etc are now pretty inefficient with needing to go via Lincoln.
So needs must, and they used a 180

We've even had a class 70 turn up twice in conjunction with the route learning on 10/05/13 and day after. Please excuse the rubbish photo as it was taken on my phone!