In the late medieval and early Tudor periods windows in smaller houses were generally unglazed and fitted with internal shutters.  Only the wealthy could afford window glass. Occasionally in the better-class houses windows of traditional Gothic form, with arched stone heads, are found, similar to those in medieval churches, but normally the windows in smaller houses were square-headed and divided into lights by stone or, more often, timber uprights or mullions, square in section and set diagonally.  This form of window survived into the seventeenth century for less important rooms such as pantries and dairies.

By the mid sixteenth century window glass was within the means of the builders of medium sized and smaller houses, and the design of the early mullioned windows was modified to take glazing.  This was in leaded panes, rectangular or diamond shaped, with iron opening lights (see Antiques Arcade, 26 High Street).  The mullions themselves were modified.

In better-class houses and in areas where stone was easily obtained, the mullions were usually of stone.  In smaller houses and in all timber-framed buildings the windows were still of timber, the mullions being similar to those of stone, but generally lighter in section.

The earliest glazed windows had mullions with straight splays, but these were soon superseded by those having a slightly hollowed splay, giving a rather lighter effect.  This detail was typical of the late sixteenth century and the early seventeenth century.  Later in the seventeenth century this section had given place to one with a convex moulding, with square fillets at the angles.  In some areas, however, the hollow splay was revived in the late seventeenth century, but by this period a plain square section mullion was more common, and continued in use into the eighteenth century in some places.

In the sixteenth and seventeenth centuries the windows were normally finished with separate hood moulds or weather moulds above the windows heads.  This feature, originally intended to protect the windows from rainwater running down the wall face, was also treated as a decorative feature.  By the late seventeenth century these separate hood moulds were often superseded by a continuous moulding over all the adjoining windows, and this feature developed into the fully continuous string course, or band course, marking the storey heights.

In the eighteenth century, in brick buildings, the last vestiges of this feature may be seen in the projecting band of three or four courses of brickwork at the various upper floor levels (see 109/110 High Street)

The proportions of the early windows were generally rather long and low, with a horizontal emphasis.  By the mid seventeenth century this proportion was changing particularly in the larger houses and those showing the influence of the Renaissance;  the windows were becoming taller and narrower, probably echoing the increased ceiling heights now becoming popular.  The windows of this type were often only two lights in width, and as well as a vertical mullion they had a horizontal member, a transom, forming a cross in the window opening.  In the smaller houses and cottages, less affected by changes in fashion and retaining lower ceiling heights, this change of proportion was less marked.

By the eighteenth century the mullioned and transomed window with its leaded lights and iron casements had, except in some rural areas, given way to the double-hung timber sash window, divided into small panes by glazing bars, so typical of the Georgian style.  In early sash windows the frames were flush with the outer face of the wall, and the glazing bars were quite heavy in section, the mouldings being a smaller version of the convex moulded mullions of the previous century (see 129 High Street).

The London Building Acts of 1707 and 1709 required the sashes to be set back four inches from the wall face, and this change later affected other parts of the country ( see Bridge House, 1-132 High Street). 

Another change may be seen in the design of the glazing bars, which became progressively lighter in section, and very slender indeed by the early nineteenth century.

In the seventeenth and early eighteenth centuries window surrounds in brick houses were often enriched and emphasized with contrasting brick dressings, and their arches were given projecting, sometimes carved keystones (see 107 High Street).

Later in the century these features were less common, reflecting the general trend of simpler facade designs.

The London Building Act of 1774 required the window frames not only to be set back from the wall face but to be recessed behind reveals, so that little of the frame was visible externally.  As with the earlier changes in London, the fashion was eventually adopted in other areas.

By the late eighteenth century other glazing patterns had appeared.  Glazing bars might be arranged in a Gothic pattern (see 34 High Street).

In the early nineteenth century one popular design had fairly large panes in the centre of each sash, with a border of narrower panes (see 95 High Street). 

By the mid nineteenth century, plate glass became available, glazing bars were omitted and the sashes were glazed in a single sheet.  At this time, too, many earlier windows had their glazing bars removed, rather spoiling the appearance of the building.

In the smaller houses and cottages the old mullioned windows were often replaced in the eighteenth century by side-hung timber casements, or by horizontally sliding sashes, both of which were cheaper to construct than the double-hung sashes, and which suited the more horizontal proportions of the windows in these houses.  Some earlier windows actually had their mullions cut out to accommodate timber sashes.  In other cases timber sashes were fitted between the mullions, replacing the lead lights and iron frames.

When blocked windows are found in old houses it is often assumed that this was done during the period when the Window Tax was in force, from 1695 to the end of the eighteenth century.  This is certainly true in some cases, but it is not the only explanation.  Sometimes a blocked window indicates an internal replanning whereby the window has become redundant ( see 38, 95, 100 High Street).  This can only be checked by an internal inspection.

Antiques Arcade, 26 High Street, Feb 2007 showing rectangular leaded panes (or "lights")

109/110 High Street, Mar 2007 showing string course of four courses of brick at 1st and 2nd storeys

129 High Street, Mar 2007, showing Georgian timber sash windows flush with the outside wall

Bridge House, 131-132 High Street, Feb 2007, showing Georgian timber sash windows, built four inches back from the wall face

107 High Street, Mar 2007, showing decorative brick dressings over windows

34 High Street, Feb 2007, showing tripartite sashes on 1st floor, and curvilinear sashes on ground floor. Built

95 High Street, Mar 2007,
showing large central panes,
with narrow side panes