That goes for any "unconventional" outdoor sports really (i.e. anything that's not footy or horses). North is always up for crazy random shit, but good luck explaining paddleboarding or mountainbiking to someone in Cambridgeshire.
I can’t speak to Cambridge specifically but there are 4 B1KE mountain bike parks alone in the south of England (Wind hill, Rogate, Tidworth and S4P) so I’m not convinced of this north/south divide. There are others than just B1KE mountain bike parks too.
To be fair, you'll have a hard time explaining anything involving mountains to someone in Cambridgeshire.
...Suffolk Mountain Rescue has been established with the aim of rescuing a neglected mountain and bringing it back to safety.