Been doing some digging on this, as it is fairly local to me and i had never heard of him.
Can't find much on David Halley, However there is someone (His son?) called Paul Halley running Pegasus Parts. They make brand new bulkheads for Series Landys i belive.
Having looked at Pegasus Parts website before, they are bloody expensive. If you need parts and are down this way, i would recommend going to Insideout 4x4 in Capel