The weather forecast is good, and it's here mid-morning not at dawn.

Only two Great Western Railway Castle class locomotives have hauled trains from Kings Cross station, the second was 7029 Clun Castle in 1967. Clun Castle will once more be travelling up the East Coast Main Line to Peterborough and then to Lincoln. It will also be the first time this century that Vintage Trains’ Pullman Cars will be back working on the main line out of Kings Cross – a route they were built for in 1960.

A fuller write-up from the tour organisers here: https://vintagetrains.co.uk/express-train-from-kings-cross-to-lincoln/

Live train times here: https://www.realtimetrains.co.uk/service/gb-nr:U91805/2023-10-07/de... 

With its copper-capped double chimney and polished brass safety valve cover it has a striking appearance. Unusually the locomotive was purchased from British Railways in 1967 in working order rather than being rescued from a scrapyard and then restored. It is based near Birmingham and usually hauls excursions to Stratford-on-Avon ('The Shakespeare Express') or in the Midlands and Southwest. 

Fuller history here: https://en.wikipedia.org/wiki/GWR_4073_Class_7029_Clun_Castle

Image: Tony Hisgett via Wikimedia Commons - licensed under the Creative Commons Attribution 2.0 Generic license.