(My bolding) -- in fact, the four stations are all LNER: Kings Cross, Liverpool Street, Fenchurch Street, and Marylebone. (I've always felt that one for each of the Big Four, would have been far more appropriate !) My understanding is that Waddingtons Games, who in the 1930s launched the (originally US-devised) game in Britain: were based in Leeds, and had in more than one way, links and associations with the LNER; that company therefore, particularly "on their radar".
@SteveM70: (you posted as I was composing this one) -- to do with the Big Four: viz. as above, one particular one thereof.
They were all LNER termini?
That’s right. Calthrop got there first and also has the reason