By Guy Taylor Shares in Chamberlin plunged 20 per cent this morning after it hiked prices and announced a wide-ranging cost cutting programme to tackle a slowdown in demand. The Walsall-based firm, which sells iron castings and engineering products, said underlying demand over the third quarter had been lower than expected. Lower sales also “negatively affected profitability and working capital,” the company said in a statement on the London Stock Exchange. As a result, Chamberlin said it would implement a “programme of cost reduction actions” across the group, including “labour reductions,” s…