Some UXO contractors try to exagerate the risk of UXO in the UK by making reference to the quantity of UXO that is discovered overseas, especially in Germany. It is true that there have been numerous fatalities on mainland Europe due to UXO, but it must be remembered that there are significant differences between the situation on the Continent and in the UK.
The CIRIA C681 guide estimated that the scale of German bombing on the UK was 20 times lower than the Allied bombing of Europe. In 2011, it was estimated that 5500 items of live ordnance (an average of 15 each day) were discovered in Germany and most were air dropped weapons. Another estimate suggested 2000 tones of munitions are found each month in the country. The wartime explosions were sufficiently strong to be felt in the upper atmosphere. In the fifty years following WW2, 630 French "deminers" were killed, many more casualties than were experienced in the UK.
The Germans preferred to use electrical fuses (with a limited battery life) rather than the Allied preference for mechanical fuses, which pose a greater hazard in the long term. Much Allied bombing took place whilst the Germans were retreating and their forces were relatively disorganised, making accurate reporting and disposal of UXO less likely. The First World War’s land battles, which used huge quantities of ordnance, were never replicated in Britain, so do not pose a threat for us. The huge difference between the discovery rate and incidence of casualties makes meaningful comparisons between our countries difficult and can be misleading.
It is interesting to note that over 1000 unexploded 18th century rockets from the East India Company were recently discovered in southern India - UXO has been a problem for a long time!