What i didn't add before is that radios and mobile phones do not work everywhere. There are significant black spots around the UK so shouting help will be more useful than having a radio. Not even AIRWAVES (tetra) is the answer. I does reduce the number of black spots but they're still not sat. phones/radios. Deep in a valley with large hills/mountains either side negates the abilities of many cordless communications systems. Even in the concrete jungle comms. are still hit n miss.