After petrol rationing ended in 1952, the BTC was aware that more swingeing cuts had to be made, and a sinister message was conveyed by the loss of the meandering 38-mile route from Blisworth to Stratford-upon-Avon in April 1952, and the 25-mile Abergavenny-Merthyr Heads of the Valleys line in January 1958.
Source: wiktionary