i carry £10 when i'm out on the bike
for emergencies, i never stop in a cafe or pub. personally i just ride, can't afford to and don't see any appeal to stop personally
the most important thing for me in life to always have with me (whilst it does sound sad) is my phone, not for facebook or snapchat but for emergencies. if i'm out driving a tractor down a busy A road and my total rig weighs over 20 tons the very last thing i want is to be stuck on a blind corner with a puncture and no way of contacting a local mobile agricultural tyre company
same on the bike, if god forbid my frame were to snap or a wheel just collapsed or i had an emergency medical issue the last thing i want to be is stuck in the middle of bugger all or sprawled over the white lines of a busy A road with no way to contact either 999, family or friends... and no the public does not always stop to help as i have found out once or twice :/
especially important for me seeing as my life is the highest risk and highest death rate industry... farming. a tenner is so good, a grand is even more useful but it still won't get you out of the very worst situations!
Cheers Ed