Watkin was also director of the Manchester, Sheffield and Lincolnshire Railway (MS&LR) and had plans for a 99-mile (159 km) London extension to join the Met just north of Aylesbury.
Watkin var også bestyrelsesmedlem hos Manchester, Sheffield and Lincolnshire Railway (MS&LR) og havde planer om en 159 km forlængelse til London for at slutte den til Met-banen umiddelbart nord for Aylesbury.