Ahh I forgot about them! However Berwick and Dunbar will be off this list soon when Reston opensBelieve it's just 35 minutes, if you exclude the 2 minutes dwell time at Carstairs.
A handful of others...
Berwick upon Tweed to Dunbar is typically 21 minutes.
Penrith North Lakes to Oxenholme Lake District is usually 22 minutes.
Similarly Hereford to Abergavenny is sometimes 22 minutes.
And one more... Sanquhar to Dumfries is usually 26 minutes.