Fears of a further weakening in global car and truck production and a sharp fall in the price of platinum from record highs in March prompted Johnson Matthey to predict a contraction in second-half profits following a strong start to the year.

However, shares in the autocatalyst maker and specialist metal refiner rose by 106p, or nearly 15 per cent, to 828½p on strong interim figures and reassurance that it expected full-year earnings growth to remain in positive territory.