Robin9 wrote:

That must be a fairly recent development. I never seen that
and I visit Kings Cross every few weeks. Obviously this will be
helpful for passengers needing to decide from which station
the next train will depart.

Not just the next train, but the first to arrive at their destination. For
example, it shows that there's a train boarding on platform 10 for
Cambridge, but there's one 10 mins later from St Pancras that gets to
Cambridge eight minutes earlier.