"I will give you three bona fide Travellers Fare sandwiches, all made within the past twenty-eight days and still recognisably triangular in shape..."
What goes up, must come down. 31419 and 31413 provide unusual power for the 16:28 Sundays only Paddington - Hereford, on 24th May 1981.
Gen. Advance information relating, in the context of this article, to specific railway vehicles on specific train services. In particular, anything unexpected.
Even though we now live in an age of information overload, it's still not a given that we'll be able to find out what's going where until it's been and gone. But railway gen is a lot more accessible in 2021 than it was in 1981, and sweeping changes to the way the railway operates have meant that most of the chaseables now run outside of the working timetable.