They all went bust within a few seasons of joining the league. All 3 of them citing the costs of running a team in the league as the reasons.
All had run for decades happily without it, so YES, the National league definitely was a major factor in th 3 clubs going bust. They all would have been better off without it.
Barry were a different issue- they just went mad with ideas they could never sustain.
In hindsight a league with a North and South conference with end of season play offs would probably had been a better idea at least for the first few seasons