Our leader and wayfinder has asked me to comment on this exchange. Yes, we could have travelled via Peterborough Crescent but we would still need to reverse at Peterborough East.
So Peterborough East can stay, then... Would I, likely, be lynched for raising a possible alternative means of getting the desired result: carrying on southward from Peterborough North, then at Fletton Junction taking the south-to-west connecting line which joins Peterborough East -- Northampton, a little way westward along its route

?