Wasn't the NDL seen as being "too good" by those in the top two tiers?..
I used to go and watch the Colts with my then under 16 lad and it cost me a tenner for the both of us to get in .
Brilliant value for money and the racing was often on a par with the top tier stuff you paid out almost three times as much for...
So much so, I barely watched the Guestfests in tier one and, instead, went most meetings to watch the NDL Guestfests, (perfectly ok at NDL level as it gives riders track time)..
I would suggest that the issue wasn't that the NDL was too good, but maybe it was the top two tiers that weren't good enough....
For me, clubs like Birmingham and Workington were perfect for NDL level racing as when they moved up the costs grew but the crowds barely did ..
Best of luck to all those under the NORA umbrella...