THE FIRST y fuze was encountered in 1943 at Lords Cricket ground , it was in a 500sc bomb. this fuze was designed soley for one purpose , namely to kill the BD officer , sent to deal with it, the fuze looked like any other ECR fuze , but it had the extra letter Y on it , as fuzes did often have variations of markings it didnt worry the officer unduly, but there the similarity ended the fuze contained a seperate cicuit, powered by two 1.5 volt cells only , this circuit came into operation after the bomb came to a complete standstill, for this fuze had 3 mercury switches, set in different planes , therefore the slightest movement, and this mercury would detonate the bomb , it was later found out that this fuze had a broken solder joint which meant it was not armed. once found how it worked Major John Hudson , and a team of scientists discovered that the fuze could be immunised by freezing the batteries using liquid Oxygen, dripped over the fuze until a Hoar frost 12 inches in circumfrance , then and only then was it safe to remove.