The 128 only ran about every two hours (with some extra weekday peak and Saturday journeys). The Bedford-Northampton section was very much in two separate sections - Lavendon-Bedford, whose residents looked towards Bedford, and Yardley Hastings to Northampton, whose residents looked towards Northampton. Outside of weekday peak and weekends, there were few passengers on the buses between Lavendon and Yardley Hastings.
These two sections were complimented by other services, 129 Northampton-Yardley-Olney-Newport and 130/1 Bedford-Lavendon-Olney-Newport and beyond. Together, the 128 and these routes offered approximately hourly service over each section. There were a few early and late journeys which ran as 129 from Northampton to Olney and the 130 from Olney to Bedford, and vice-versa, for historical operational reasons that we needn't go into here. There was also another local route, 133, from Bedford to Bromham Village, that went via Biddenham and then deep into Bromham, far from the 128 routeing on the A428.
So what changed? The character of the intermediate villages changed from the 60s to the 80s into affluent places with high car ownership and little need for buses. Education changes, particularly comprehensive schools and therefore common catchment areas, meant that Grammar School children no longer had bus passes to travel by service bus into the big town, but went in contract vehicles to village comprehensive schools. By a quirk of boundaries, Lavendon is in Buckinghamshire [but far in distance and character to Slough!] and in the Milton Keynes council area. The pull of the (then) new Milton Keynes employment and retail, both from Lavendon and the surrounding Beds and Northants villages meant that fewer journeys were being made to Bedford or Northampton.
In 1974 the 128 was operated mainly by crew operated Lodekkas (although some OMO VR types were also in use] and the journey from Bedford Bus Station to Northampton bus Station, via Bedford Midland Road Station took 59 minutes. Aside from the slightly longer route via Midland Road Station, the route followed the most direct road (A428) which was the main East-West commercial vehicle highway. It turned off into Yardley Hastings and Denton villages, both by-passed in early road improvements. It had to cross the narrow Bromham Bridge and encountered two roundabouts (Prebend St Bedford and Warrington Toll Bar), 2 or 3 sets of traffic lights and no traffic calming en-route. A pretty comfortable ride, as I recall.
Just look at it now - the 41 covers the 133,130/1 and 129 routes, and diverts via Biddenham, a serpentine route through Bromham Village and the long diversion via Olney and The Aspreys along bouncy rural roads. Yardley Hastings now is served from a by-pass stop and Little Houghton village has been by-passed without replacement. Denton is still gone round, even though it is extremely awkward with parked cars and narrow lanes. Bromham has been comprehensively by-passed, but the bus doesn't use most of that. How many roundabouts, traffic lights and traffic calming features now, traversed in a jerky, automatic bus being driven flat out to keep time, the passengers bounced around like peas in a pod? The overall journey time from Bedford to Northampton has increased to 1h25min. And we wonder why few want to use this bus nowadays?
Sadly, this scenario can be seen all over the country.