Charles Stanley keeps its 'hold' on temporary power supplier Aggreko despite a "very positive" first quarter update, due the stock's recent strong run."Aggreko has issued an interim management statement for period from 1 January to date which is better than expectations both in terms of revenue growth but also with a stronger market background leading to increased capital expenditure guidance and hence a better growth outlook for 2012," said analyst Tony Shepard.Revenues grew by 9% in the quarter to 31 March. Excluding revenues from major events (such as the Winter Olympics/World Cup), underlying revenues have grown by 18% in constant currency and excluding pass-through fuel, the broker notes.However, Charles Stanley highlights that the share price has performance exceptionally strongly and is already on a full multiple of 21 times 2011 earnings.---bc