Gradually the goldsmiths began to lend the money out on behalf of the depositor, which led to the development of modern banking practices; promissory notes (which evolved into banknotes) were issued for money deposited as a loan to the goldsmith. Banks can create new money when they make a loan. New loans throughout the banking system generate new deposits elsewhere in the system. The money supply is usually increased by the act of lending, and reduced when loans are repaid faster than new ones are generated. In the United Kingdom between 1997 and 2007, there was an increase in the money supply, largely caused by much more bank lending, which served to push up property prices and increase private debt. The amount of money in the economy as measured by M4 in the UK went from £750 billion to £1700 billion between 1997 and 2007, much of the increase caused by bank lending. If all the banks increase their lending together, then they can expect new deposits to return to them and the amount of money in the economy will increase. Excessive or risky lending can cause borrowers to default, the banks then become more cautious, so there is less lending and therefore less money so that the economy can go from boom to bust as happened in the UK and many other Western economies after 2007. The goldsmith paid interest on these deposits. Since the promissory notes were payable on demand, and the advances (loans) to the goldsmith’s customers were repayable over a longer time period, this was an early form of fractional reserve banking. The promissory notes developed into an assignable instrument which could circulate as a safe and convenient form of money backed by the goldsmith’s promise to pay,allowing goldsmiths to advance loans with little risk of default. Thus, the goldsmiths of London became the forerunners of banking by creating new money based on credit.