UK companies lagged behind their peers in Northern Europe in the year to 31 March, the private equity group 3i said in a trading update ahead of its full-year results. The firm said it had seen good progress across the whole business."Overall, the private equity portfolio has performed well," chief executive Michael Queen said. "There have, however, been marked regional differences, with strong growth in Northern Europe counterbalanced by weaker performance from UK companies."He said the regional variation was due to a combination of "macro and company specific factors."3i's investments in the UK include the toy retailer Early Learning Centre and the nightclub operator and record label Ministry of Sound.RG