The first reference about "Pocket Beagles" can be found in the Elizabethan period. Queen Elizabeth I- was known to have these type beagles. It is said that they were small enough to be carried in a glove or gauntlet. The standard of the British Beagle Club in 1890 stated "that they should be no more than 10 inches in height......should be compact and symmetrical throughout, of true Beagle type and show great quality and breeding."
The current British Beagle Standard and the current American Kennel Club Standard DOES NOT make mention of the "Pocket Beagle", at all. In England the standard reads that "the desirable height should not exceed sixteen inches or fall below thirteen inches. The American Standard has two size "varieties" 13 inches and under, or over 13" to 15 inches. Any dog over 15 inches in America can be disqualified from the showring.
The last reference to the "Pocket Beagle" I can located in a reliable reference is in the 1960"s.
While there may be a few beagles that have the genetic tendency to be very small, you must also consider whether the dog looks like a beagle or just a small dog with beagle coloring. Many structural problems, whelping problems and other genetic concerns must be considered when breeding beagles. Breeding for size only could be a disaster waiting to happen.
I would hesistate to purchase a beagle for its unusual size, especially if the breeder was wanting a higher price for this "rare" pocket beagle. One source states that a "reputable breeder" does not breed for pocket beagles. Pocket Beagles are DEFINITELY NOT a special size recognized by AKC.
FYI--you can breed two 13 inch beagles and get an entire litter of 15 inch beagles and vice versa. Or you can get a litter with some of both sizes AT MATURITY. Reputable breeders make educated guesses at 8-12 weeks of age; but no one can guarantee that a puppy will stay a 13 or 15. That would be like looking at a 6 year old and guessing if he will be tall enough to play basketball or be stocky like a linebacker.!!
Here is another link to information about "Pocket Beagles."(scroll down the page on this link)