Pinsent Masons has advised investment vehicle Horizon Acquisition on its $855m (£527m) purchase of US-based temporary power provider APR Energy.

Pinsents took the lead role for Horizon in the sale after being instructed in April, with a team led by corporate partners Rob Hutchings and Paul Amiss.

The UK firm first advised Horizon on its February 2010 initial public offering on the London Stock Exchange (LSE).

Amiss commented: "It was a good deal for all involved. It's exciting times for APR, as the deal provides the group with access to capital to accelerate its growth and Horizon's stock market listing will enhance its reputation and provide further access to growth 
capital if required."

APR and its shareholders were advised by Greenberg Traurig and Florida-based Shutts & Bowen, while US law firm Vinson & Elkins took a role for Soros Fund Management and Albright Capital Management, both of which hold stakes in APR. The investment funds are headed by billionaire investor George Soros and former US Secretary of State Madeleine Albright respectively.

Greenberg fielded a US-based team including corporate and securities partners Jennifer Westerlund and Alan Annex and a UK-based team led by London chair Paul Maher and corporate partner Gary Cooper.

Horizon was set up by Pizza Express co-founder Hugh Osmond in 2010 alongside Michael Fairey, the former deputy chief executive of Lloyds TSB.

APR is the second-largest portable power provider in the world and specialises in supplying generators to developing countries and regions suffering temporary electricity shortages. It employs more than 500 people in 10 countries.

Trading in Horizon shares has since been suspended and the company will be renamed APR Energy on readmission to the LSE, which is expected to be in September.