How about shortening all this conditional import/decorator stuff to:
```
# Since pandas is an optional dependency, we disable all these tests
# if it's not installed.
try:
    import pandas
    import iris.pandas
    skip_pandas = lambda fn: fn
except ImportError:
    skip = unittest.skip('Test(s) require pandas, which is not installed.')
    skip_pandas = lambda fn: skip(fn)
```