Quibbling I know, but I wouldn't call it 'stupidity'. Beeching knew what he was doing and he enjoyed doing it. It was for the benefit of Marples and himself, in order to support the motoring industry.
Let's give it one more try:
Dr Beeching had no interest in the motoring industry. His business life had been in chemical engineering. He was renowned as a logical thinker and had been educated at Imperial College. Unsurprisingly he was not impressed by the relatively traditional approach of British Railways as he found them.
Passenger journeys had been falling ever since the grouping.
Peak freight tonnage was probably in 1929, allowing for the fact that in pre-grouping times there may have been an element of double counting for consignments using multiple railway companies.
Passenger services had already been withdrawn from thousands of miles of route before Beeching’s time.
Despite the 1955 Modernisation Plan supposedly improving services through replacement of steam traction and other factors such as improved journey times, the inexorable decline in passenger traffic continued.
Similarly the spread of continuously braked freight trains, new marshalling yards, etc., did not seem to stem the gradual decline in freight volumes.
A casual inspection of the gradual trends of falling passenger and freight traffic throughout the 1950s and early 1960s would never lead one to infer that a massive modernisation strategy had been put in place to win back passenger and freight traffic from the roads. It had failed in this respect.
Although the Modernisation Plan was also expected to improve efficiency and return the railways to profitability, losses continued to increase. This was against a legislative framework dating back to nationalisation that did not allow for subsidies (only borrowing to cover losses and BR’s debt was spiralling out of control).
By the time Beeching took over the modernisation money had largely been spent but there were still many secondary and tertiary routes and activities that needed major investment if they were to survive.
Marples approved the closure of 1,436 miles to passenger services after publication of the Reshaping report before the Conservative party lost the 1964 general election.
Labour ministers subsequently approved closure of a further 2,071 miles. It is completely clear that in the essentially 'two party' political landscape of the time both of them agreed that the railway industry was over-trading in the face of growing car ownership, motorways and so forth.
Although the Workington-Penrith case was put to Marples in October 1963 he did not decide it and it was still in the ministerial ‘In’ tray when the change of government occurred in October 1964. Beeching left at the end of May 1965. In fact it was Barbara Castle who finally directed the closure in January 1966.
Interestingly even over the most intense phase of Beeching and post-Beeching closures the decline in traffic did not really accelerate. As Beeching had correctly identified, a large slice of the network was carrying a minimal proportion of the traffic, both passenger and freight. For all the claims that that the traffic surveys did not properly reflect contributory revenue or allow for the fact that some passenger lines were busier in summer it is still far from clear from either the overall network usage or revenue figures that significant extra business was lost from closures.
All of this is clearly articulated at considerable length in Gourvish's 'Business History of British Railways' and in various Transport Statistics reports.
And yes, I lived through it and remember how quiet many of those branch line trains were.