Imagine you're at an informal meeting at the end of which someone says their child is running a marathon and needs sponsors. With much good-natured chatter everyone passes an iimpromptu "hat" around and chucks in a fiver or a tenner. ' Till it comes to you. "Oh no! I've no change on me!" you cry. "Not to worry, it isn't till Sunday" the parent says. Your face doesn't change. Sunday you'll still be broke. "It's ok" someone else says "I just threw a tenner in for you. You can give it to me at work, later." Your cheeks blaze and you swallow nervously. How the hell are you going to finesse an extra £10 out of your next payment which, in any case, isn't for another twelve days? Or perhaps you're having coffee with someone. They get an urgent call about a breaking crisis and have to leave, forgetting they haven't even paid for their untouched coffee. NOW what do you do? In your purse