Upmarket kitchen group John Lewis of Hungerford has reported an 18% increase in turnover for the half year ended 28 February as a result of the combination of like-for-like sales growth a new store openings.However, chairman Malcolm Hepworth warned of margin pressures through raw material price increases amid an uncertain consumer environment."The current economic climate requires caution to be exercised and your board remain alert to the risk presented by continuing weak consumer confidence," said Hepworth.Nevertheless, like-for-like sales grew 9%, while core product sales increased by 12.6%. As a result, turnover grew to £2.7m, from £2.3m previously. Pre-tax loss narrowed from £0.23m to £0.13m. Loss per share was 0.07p, down from a loss of 0.12p.Despite the chairman's cautious words, the group reported that its advance order book is some 20% ahead of the previous year.