A thoroughly sensible, well-thought out, and interesting post. I'm glad you posted that.
Hmm. One advantage of a line between Northampton and Bedford is that it could link up with the Varsity Line. That would allow trains from Birmingham to Cambridge/Stansted Airport to travel via a more direct route - via Coventry, Rugby, Northampton and Bedford - as well as giving parts of the southern East Midlands a direct connection to Birmingham International.
Oh for crying out loud - not this load of old pony AGAIN.
Northampton - Bedford isn't going to happen, period. There simply isn't the demand.
The old Northampton - Bedford route was circuituous, slow and had no demand. I seem to recall the old line was about 25 miles as it went via Olney. Realistic journey time c 40 mins.
You can already do Northampton - Bletchley in 20 mins - assume a Bletchley - Bedford time of 30 mins (which I believe is what EWR are touting) - so there's no way reinstating Northampton - Bedford to save 10-15 mins even starts to make sense.
And as for improving the Birmingham - Cambridge route via using this reopening, you are of course, joking.
So you'd lose the connectivity to Leicester and Peterborough which is probably more important than Northampton and Bedford - and I take it you've seen quite how many free paths there are between Birmingham Intl and Rugby currently? I'll give you a clue it's probably less than 1 per hour.

