that fact that clarckson swapped the word out for teacher, the kind of wet lefty bicycle riding gurdianista he hates, shows that he knew it was offensive the first time he said it
im not sure if its arrogance or old age or both but he does seem to living up to his stereotype (this, + the bridge joke, + tweeting about the cyclist in kensington etc)
fwiw I always knew its as ‘catch a nipper by the toe’ when we grew up, never heard anyone say it otherwise and Id say that my family and friends were in no way PC or not prone to casual racism themselves