The British No. 4 Spike Bayonet is a type of bayonet used by the British Army during World War II. It was designed to be used with the Lee-Enfield No. 4 rifle, which was the standard-issue rifle for British troops during the war.

The No. 4 Spike Bayonet was a simple design, featuring a long, tapered spike that could be attached to the end of the rifle's barrel. It was designed to be used primarily for thrusting, rather than cutting or slashing, and was intended to provide soldiers with a close-quarters combat option in case their rifle's ammunition ran out or became ineffective.

The No. 4 Spike Bayonet was made of steel and had a length of approximately 8 inches. It was designed to be lightweight and easy to use, with a simple mechanism for attaching and detaching it from the rifle.

The No. 4 Spike Bayonet saw extensive use during World War II, particularly in the later years of the conflict when the British Army was engaged in close-quarters combat in urban environments. While it was not as versatile or effective as some other types of bayonets, the No. 4 Spike Bayonet provided soldiers with a simple and reliable option for close-quarters combat.