That this screen dates from the first half of the fifteenth century, maybe, perhaps, as early as about 1430, I infer from the character of its fenestration. The latter, consisting of a single panel of pierced tracery in each bay, is an exact counterpart of the stone window-tracery of the period. It differs from the method of timber screen construction evolved subsequently, in which the muntins run from top to bottom of the openings, and in which the effect of tracery in each several bay-head is obtained by a combined series of separate units of pierced work let into grooves sunk in the upper part of the muntins. In the Chesterfield rood-screen, on the contrary (as also in the fourteenth century rood-screen at Kirk Langley, already described), the upright shafts in each bay merely support from below the tracery above in the head, instead of holding it in position as between two sides of a frame. Neither, again, in the Chesterfield example does the spacing of the batement lights correspond with that of the three lights at the bottom. The uneven number of the latter is abnormal. It became far more usual, as timber screen-work developed, for the fenestration to be divided by a central muntin into two lights (as at Breadsall and Fenny Bentley), or (as in other parts of England) for the central muntin, remaining a constant factor, to be supplemented by one pair or more pairs of muntins, as the case might be, so that the number of lights comprised in a single bay would, in all events, work out to an even number.