Lewis Wright says that the true Birmingham Roller "turns over backwards with inconceivable rapidity through a considerable distance like a spinning ball," and this sentence provides an excellent standard for the performance of a Birmingham Roller.
During my experience, I have always found a total ignorance regarding this standard, and yet it is quite plain in its interpretation. Let us examine the set and precise performance of the standard roll. During flight the bird makes a series of backward somersaults so rapidly that it is impossible to count the revolutions. Each revolution is so close to another that the bird rolls or wraps itself up like a small ball as it revolves at terrific speed in a straight line downwards.
A side view of the bird in action will reveal the presence of a small hole, about the size of a two shilling piece, and unless this small hole can readily be the bird not a first class Roller and should be valued accordingly insofar as its breeding qualities of the roll is very important, probably the most important feature of the performance.
I do not hesitate in saying that a distance of fifteen yards is the physical limit of a first class bird, if it values the pleasure of living. This is deep, in fact very deep, and more than a dozen birds of this nature can not be flown without serious casualties among them. The best and most spectacular is one of six to eight yards, if a fancier wants results from his efforts.
Twenty birds rolling in the correct manner, with six to eight yards as their limit, will give such an exhilarating exhibition of concerted acrobatics that the imagination can not describe it. Such performance is by no means impossible and should be the aim of every fancier devoted to the Birmingham Roller.