I still don't understand why the rule calling CF_TO_LBFC has been singled out here.  Why not all of the 8 other rules which can populate lbfc??  Surely we wouldn't extend the conditional statement above to encompass the outcome of all of these rules too??

These other rules can also be overridden by the CF_TO_LBFC or STASH_TRANS rules...  This is currently where pp_save_rules.txt sits, whether we like it or not.  Taking all other 8 rules into consideration as I believe you would have to, following the above argument, is totally out of scope for this change.

Example rule not under consideration:
```
 69 IF
 70     pp.lbfc == 0
 71     cm.name() in ['geopotential_height']
 72 THEN
 73     pp.lbfc = 1
```