There's your answer: the pointwork for which Minories was designed was nowhere near as generous as 1 in 7. Even today, Setrack points curve through 22.5° (which if my maths is correct is something ridiculous like 1 in 2.4) at 17 inches radius, and some sectional track in 1957 was likely tighter still. Along with the tight curves, flangeways were wide and wheelsets had loads of sideplay. Minories was a very practical solution for its context, while remaining railwaylike, which is a signature CJF characteristic.