Indeed it is still up north and its in northamptonshire
In a width of 400 meters the A5 road, Grand union canal, west coast main line railway, and the M1 motorway all traverse the gap in parallel.
And it was the first motorway service station in the uk, it is stated that corby the first largest town north of the watford gap as the "gateway to the north" or in other words and sometimes called the north/south divide