In London, they used to have the Cappuccino Index to gauge which areas where on the up and which were on the down – the sudden availability of froth-topped, good quality Italian coffee was seen as a solid indication of an imminent middle-class presence in an area (and therefore an indicator of likely house price rises). The Economist magazine had its Big Mac Index to compare exchange rates – as Big Macs internationally are broadly the same, differing prices in different countries showed the gap in how currencies are valued. For me, a bit of ‘car park economics’ is a very useful way to gauge how the economy has been performing. What people have been buying to get themselves from A to B – the size, brand, price and country of origin – can tell us a lot about everything from the strength of the Korean Won to the price of a barrel of Brent crude.