As noted above... : https://github.com/SciTools/iris/pull/1115/files#r12333428
... I'm wondering if we could skip the numpy-ish bit here somehow, and load straight as a Python list (both longs + floats) for the header data.
It's probably very inefficient to have "tuple(<array>) + tuple(<array>)" as it was before, though.  Maybe there's a neat+efficient way of bypassing the numpy load here.  Or maybe not...