I would just like to thank those who have replied, particularly the comprehensive reply from
@RT4038 - I think I had read somewhere that United Counties (UCOC) had for some reason not been able to provide a service. I am gobsmacked (but this is my own ignorance of the era) that UCOC struggled with resources and recruitment - I would never have suspected that was the reason, so thank you for that insight.
I was still surprised that there were double the number of trains in 1967 on this section - given the relative insignificance of Bletchley in 1967. Am I just right in assuming that the other sections were/are even more rural than this section?
United Counties, and indeed most other bus companies in and around the London-Bristol-Midlands triangle (and some far outside, also!) suffered from staffing shortages in that era. The basic reason was that bus crew wages and working conditions could not compete with other industries in the area, during a time of full employment. The expedient of increasing wages was not available, due to the (by then outdated) regulation of timetables and fares, making reductions of the former and increases of the latter difficult and slow to implement, and the sharp decline in passengers in the late 50s/early 60s caused by televisions, fridges and car ownership. Bus crew wages were also negotiated nationally, with the result that in Padstow and Pickering bus work was some of the best paying work available, whereas in Bedford and Oxford staff could not be got for love nor money. Bus companies could improve wages by increasing efficiency, but the main method available was increased one-man operation, fought by the older (majority) members of staff and constricted by the purchase and delivery of suitable vehicles.
At the time of both the '67 & '73 closure attempts, Bedford Depot would have been about 20% short of crew. Bletchley, a small depot, probably not much better. The Bedford-Bletchley replacement bus service required (I think) 3 vehicles all day + 3 extra during the peak period. At the '67 attempt, this would been exacerbated by the two depots requiring to find crew for the extra 2 buses (one each) on the Oxford and Cambridge services (two places with severe shortages of their own!).
It is hardly surprising that United Counties didn't go into the replacement service with alacrity - finding the six extra vehicles which would have been one-man from the start, taking vehicles away from the conversion of existing services, and finding the additional drivers near impossible, with adverse effect on their other services. New vehicles, if the capital was available, which it wasn't, would have had a three year lead time, if they could be manufactured at all. At the time of the '73 attempt United Counties was reeling from the effects of purchasing Luton Corporation Transport, with its attendant staffing and particularly vehicle problems.
With the costs of such 'peak' boosting [vehicles and staff only used for a small part of the day] probably rendering the whole service uneconomic, the bus company would have had a feeling that the Railways were trying to offload their financial problems onto them!
Amazing as it might seem now, the Bedford-Ridgmont section of the line was lined with brickyards, pouring noxious gasses into the atmosphere, as anyone who lived in Bedford in that era would have smelt all the time. There were two large brickworks at Kempston Hardwick (?Eastwoods? and Coronation), the super works at Stewartby (London Brick), the Marston Valley works at Ridgmont (Brogborough) and several smaller yards. These were large employers, particularly of Polish, Italian and Pakistani immigrants, the descendants of which are still in Bedford to this day. Some lived in company housing at Stewartby and Brogborough, but many were conveyed by contract buses of Horseshoe and SM Ementon, or travelled by train. Of course the yards started to mechanise and employment reduced, and then pollution control started to close the traditional brick making down, to the current positon of there being none. Bedford also has a number of very popular private schools, which contributed lots of traffic from the affluent areas around Woburn Sands & Aspley Guise, and the area west of Bletchley. The other sections, Bletchley-Oxford and Bedford-Cambridge were much more rural in nature, and the Bedford-Sandy section particularly well catered for by buses.
To be fair, I didn't say it was a physical inability - nor was that what I meant.
Apologies - I thought you were referring to the inability to serve the villages, rather than the (end) towns, which the bus company couldn't connect either, for the reasons above.
Bletchley was a main junction and had some Inter City services at that point.
Bletchley was 'relatively insignificant' as a place compared to Bedford, and was not a main junction from a passenger traffic point of view at that time. It was significant from a railway operating point of view, being the location of a locomotive depot and junction. I suspect the few Inter City services that did stop there were more for parcels and mail traffic than passengers.
Milton Keynes was only incorporated in 1967, and was contributing insignificant traffic by the '73 attempt. Bletchley did have some overspill housing (Lakes Estate) and industry, and was clearly a significant traffic objective from Woburn Sands. I recall that Bletchley booking office had single tickets to Woburn Sands issued on an 'Ultimatic' machine, which shows the sales must have been a fair few. At that time the branch only did single tickets within the branch, so presumably a London-Woburn Sands or vice versa journey was rebooked at Bletchley, which might account for the number of single ticket sales.