SlinkyCat, I agree that 7" may well be impressive but unfortunately not as a dogs tail, unless of course it is an extremely small JRT
He certainly looks a right little character :-)
My last Parson Jack Russell had a tail well in excess of 12" but was quite high on his legs as would have been appreciated by the Parson himself, especially as he was also named after the Parsons first terrier "Trump" and more importantly he could keep up with the pack of hounds and would go to ground and bay like there was no tomorrow, A true terrier even in the eyes of the Parson.
A small, short bow legged, barrel chested terrier with a short tail would not have earned the respect of the name "Jack Russell Terrier" by any terrierman of note, myself included but these days are gone, these days any small dog with a patch of brown will be called a JRT.
At the end of the day it doesn't matter what you call him, he is your pet and im sure you will love him whatever his attributes, he certainly looks like a mischievous character of true terrier tenacity :-)