I think it's more complex than the simple rule that countable nouns take 'fewer' and uncountable take 'less'. It seems to me that when we are talking about 'one' then we more comfortably use 'less': for example: 'that's one less to worry about'; 'one less cup to break' etc. This must be true, because everyone so far has said that this sounds better to them than using 'fewer'. We also say 'there's one less reason' not 'there's one fewer reason'.
Farage fails to report 5 million gift!


