I had a method that was taking (Int32 masterID), this
has been changed to ( Long masterID ).

However no matter what I do I cant get the project
referencing the class to see it as Long and not Int32 -
it keeps on giving me compile errors, even though I have
unreferenced, rebuilt ...

I haso have the same problem with a class not being
recognised in a referencing project (have checked the
namespaces), but will not see the new class.