For Patatty and Bingley and interested onlookers, Mr Fowler in his own words (or Gowers's?):

The English-speaking world may be divided into (1) those who neither know nor care what a split infinitive is; (2) those who do not know, but care very much; (3) those who know and condemn (contemn? grin); (4) those who know and approve; and (5) those who know and distinguish.

He says that those in group (1) are the vast majority, and are a happy folk, to be envied by most of the minority classes.

He chiefly addresses his comments to those in group (2).

Group (3) he says are bogy-haunted creatures …

Group (4) are not distinguishable with certainty.

Group (5) will split infinitives sooner than be ambiguous or artificial.

But, as Patatty says, you really have to read his comments (and examples) in full to get the flavour. As he says, "the author's opinion has perhaps been allowed to appear with indecent plainness".