The "Miracle at Dunkirk" in Northern France that saw many British and French lives saved under the threat of complete annihilation by the Germans and cost the Allies much in the way of war-making equipment including highly valuable anti-tank guns lost to the enemy in the hurried escape. This put a vast amount of political and manufacturing pressure on Britain who entered into a mode of self-preservation with the assumption being that the German war machine would soon enact plans for the take-over of England itself. As such, many projects were evolved to provide the most basic of weapons to the largest collection of users possible - from frontline military forces to the Home Guard and even civilian units for the final defense of the island nation.
To shore up the stock of the lost tank-killing guns, a lost-cost-yet-effective anti-tank solution was unveiled in the "No. 73 Grenade" - a thrown, cylindrical-shaped hand grenade capable of defeating up to 2" of armor - enough to destroy light-class enemy tanks and similar combat vehicles though at uncomfortably close ranges. Its size limited how many could be carried into battle and it also limited throwing ranges to just under 15 years or so depending on external factors. Regardless, the need was great and the No. 73 seemingly fit the bill.
Adoption of the weapon occurred during the latter part of 1940. Its general cylindrical shape quickly netted the product the nickname of "Thermos Bomb" or "Woolworth Bomb". An outcropping at the top was the safety cap which housed the detonating facilities of the grenade including its spring, needle, and safety bolt. The explosive filling (either Nitrogelatine or Polar Ammonal Gelatine Dynamite) made up the remainder of the cylinder. A detonator tube ran from the detonator to the filling. The grenade body was fabricated of tin with an inner wax paper wrapper. A stream of adhesive tape - used during the throwing/arming process - hung free along the side of the grenade and was held by the operator when hurling the grenade, the tape pulling the firing pin. Overall weight was a hefty 4.5lbs (considering other infantry equipment expected to be carried) with an overall length of 11 inches and a diameter measuring 3.5 inches. Actual detonation was through a simple impact process.
The No. 73 grenade held a very short service life during the war for it was given up (at least in its intended battlefield role) before the end of 1941. By this time, however, it was already found that the grenade could prove serviceable as a demolition charge for engineering units and was brought into use again for 1943. The grenade then ended its days as such and was formally retired from frontline use in the last year of the war - 1945. The anti-tank killing function during the course of the war fell to various other solutions in play - shoulder-fired rocket launchers, anti-tank rifles, landmines, self-propelled tank destroyers, and towed anti-tank guns.