I belive that this route can be set in the present 2023 with LNER class 91s and class 80X with a themslink class 700 or 701. It could also be set in 2016 with the Virgin rail hst and class 91 with other themslink EMU's for the stopper selection. For the freight you could have a GBRF class 66, DB class 60 or even a freightliner class 90.
Great suggestion and welcome to the forums! I'd love this part of the ecml in the game. But for future suggestions try to add a bit more detail to them
It may not happen. with 2023 era with LNER. Could either be East Coast, VTEC, or GNER would be nice. Not the class 800's also it would be nice to put more detail and due to the spelling i think your youngish. Don't think we will see class 90 on ECML. Thameslink's Class 700 would be nice. Also thinking if Great Northern's or Back dated First Capital Connect. FCC Out of King's cross to Cambridge And GNER or EC To Peterborough and AI up and beyond would be nice.
I would love to see the ECML in game, though preferably in the 80s. Also if it does get done modern the best year to do it would be 2019 as you could have the 801s, 700s and GWE HST in the LNER condition providing something for modern emu lovers and those who like diesels.