De-Activated Mills No 36 MKI Hand Grenade.

The No36 Mills grenade was the standard grenade issued to British soldiers from May 1918 until the 1970's, 

The original Mills  grenade was Patented by William Mills in February 1915 

No36 grenade was issued from May 1918 and the main differences were a more rounded body to fit into a grenade discharger better and stronger safety pin ears

This is an De-Activated grenade and was manufactured by A. Kenrick & Sons, West Bromwich and has the appropriate makers mark (K in stars) on the front.