These are specialised chisels designed to cut the ‘pocket piece’ in the side of the frame of a Sash sliding window. The pocket piece is a removeable wooden ‘window’ to enable access into the space at each side of sash windows in which run the sash cords to raise/lower the window. These cords, over time, wear out and need to be replaced. Without this ‘pocket’ to access the cord and ‘weights’, that would not be possible.
Do not confuse these with Sash Mortice Chisels which have nothing to do with Sash windows but are themselves merely lighter duty Mortice Chisels.
The first reference that I can find to the availability of Sash Mortice Chisels is in the 1897 Catalogue, but they may have been available before then. They seem always to have been offered for sale ‘Handled’. In 1897 the variety of wood handle is not stated, but would probably have been Beech. Listed there is Item# 1980 Sash Pocket Chisel [SPC] in widths of 1.1/2-2.1/2″. Item#1980A is the Improved Sash Pocket Chisel [ISPC] in the same widths.
The 1909 Catalogue shows an item# change; SPC becomes #880 and ISPC becomes #881. Both with Beech handles and the same widths available as before.
The 1921 Catalogue shows a reduced output [as found in most of the MARPLES line] in that only #881 is listed, in Beech and the same widths as before.
By 1928 both lines have been listed [#880 and #881] and in the same Beech handles and the same widths. The 1938 Catalogue shows exactly the same details.
The 1959 Catalogue only lists the Improved Sash Pocket Chisel [#881] and in the 2″ size with an Ash handle.
The last listing I can find is in the March 1962 Price List as a 2″ width at 13/6d.
Sash Pocket chisels shold only be sharpened on one side, like a normal chisel. This is important in this guise because it is required that the chisel maintain its’ line and not deviate, as may be possible if it were sharpened on 2 sides. You may often find these chisels wrongly sharpened. Of the 2 styles of chisel here, the Improved variety is less commonly found. At this stage [4/20] I am unsure that the handle style denotes either a Common SMC or an ISMC, as I have both handle styles with SMC blades. Therefore I must now assume that at some time, MARPLES interchanged the handle styles, and it is therefore only the metal forging which dictates the style.