UNILEVER, the Walls ice cream to Persil giant, enjoyed a 7 per cent increase in first quarter earnings with sales of food and personal care products in continental Europe providing the engine for growth. Pre-tax profits in the three months to the end of March climbed to £538 million sterling from £503 million in the corresponding period last year. At current exchange rates, net profits fell 8 per cent to £296 million, reflecting the relative strength of sterling.