Key blank, a key, and a cylinder lock and key combination

A key blank configured to fit into a keyway of a cylindrical key plug of an associated cylinder lock, comprising a substantially flat key blade, which:

• extends from a grip portion along a longitudinal axis (A),
• includes a connecting portion, a major longitudinal bitting portion to be provided with a row of coded cuts, and a free tip portion,
• has a cross-sectional profile which, in said major longitudinal bitting portion,
• is confined within a rectangle having a height (h), measured in a vertical direction, being at least 2.5 times larger than a width (w) thereof, and
• extends upwards in said vertical direction from a lower edge surface to an upper edge surface along a vertical mid-plane (MP) through said rectangle, the vertical mid-plane being located in the middle of said rectangle,
• includes at least two parts:
• a lower, relatively wide part, including said lower edge surface and having a maximum width, measured between a first lower side surface and a second lower side surface, being the same as or slightly less than the width of the rectangle, the maximum width being 75% to 100% of the width (w) of the rectangle,
• an upper, relatively narrow part, provided with the upper edge surface and being narrower than the lower part, and
• an interconnecting part possibly extending between the lower and upper parts along said vertical mid-plane,
• wherein:
• the upper, relatively narrow part has a lateral width being no more than 33% of said maximum width of the lower part, and extends obliquely upwards along a first direction (P1) pointing away from said second lower side wall of the lower part and being inclined at a relatively small angle α, in the interval 3° to 12°, relative to said vertical mid-plane, and
• the sideways or lateral location, within said rectangle, of said upper relatively narrow part of said key blade, including first and second upper side surfaces thereof, is such that an imaginary downward extension thereof, substantially in a second direction (P2) opposite to said first direction, will fall onto said lower edge surface of the substantially flat key blade, at a same second side of said vertical mid-plane (MP) and inside said second lower side surface of the substantially flat key blade.