Aggreko may be best known for powering high-profile events, such as the Glastonbury festival, but it is the less glitzy business of renting generators to developing countries that has been fuelling the group’s sales. The drought in east Africa contributed to a stronger than expected performance from its international power projects, which serve such markets. But the Glasgow-based company has seen sales growth in this star-performing division slow markedly, from 50 per cent last year to 10 per cent on a constant currency basis. After the company’s shares rallied by more than half in the past three months, double that of the support services sector, they hit a record this week and trade at 14.3 times prospective earnings. That is still a discount to the sector, but they offer an uninspiring dividend yield of 1.4 per cent.