The main reasons quality dropped after 1970:
1. The Oil Crisis (1973) The OAPEC declared an oil embargo against any country that supported Israel during the 1973 Yom Kippur War which sent shockwaves through global manufacturing when the price of oil increased to $12 a barrel in USA. Cost-cutting became survival, and electrical components were an easy target — cheaper materials, thinner wiring, lower-grade insulation.
2. Emissions regulations New US and European emissions laws forced rapid, expensive redesigns of engines and fuel systems. Manufacturers diverted R&D budgets away from refinement and into compliance, leaving electrical systems under-resourced.
3. Increasing complexity Cars went from simple 6-volt systems with a handful of circuits to complex 12-volt systems powering dozens of accessories. More complexity meant more failure points, and manufacturing quality couldn't always keep pace.
4. Global supply chain pressure The shift toward cheaper offshore component sourcing began in earnest in the early 1970s. Lower labour costs came with lower quality control.
5. Labour disputes in Britain specifically The 1970s were particularly brutal for British manufacturing — strikes, work-to-rule actions, and chronic underinvestment hit companies like Lucas, BL, and their suppliers hard.
6. Planned obsolescence As car replacement cycles shortened, there was less commercial incentive to build parts that lasted 20+ years.