Just wondering, why on the seat selector does it not allow you to select the same seat for the entire journey, even if it is available for the whole journey?We've not killed it off, you need to click "Add to basket" and then visit the basket (link in the nav in the top right). Click the seat icon, then click the pencil to edit next to the seat you want to change, and the seat selector will open up inline.
I've just booked a trip from Newark Northgate to Kings Cross, on a direct train. The splits are at Peterborough and Stevenage. By default it has given me one seat from Newark to Stevenage, and a different seat from Stevenage to Kings Cross. I know that many specific seats are available for the entire journey, as if I select a different seat for the first section, it will become available for the second. Similarly, if I remove the booking from my basket and go to LNER buying just one ticket, it allows me to select that seat.