I have never been to Birtley, but it sounds to have been a great club from the comments this thread. I help run the Wath Folk Club in South Yorkshire and we too are struggling.
We have changed from a weekly club to once a month with our first once monthly meeting this Sunday. We are trying everything we can to keep going, but must admit it can be hard work and I hope our new venture will succeed..
Is there not someone in the Birtley Folk Club area that can help, it certainly sounds like a club well worth saving or have all avenues already been tried?