Electra, the private equity firm that recently defeated a boardroom coup attempt by a US corporate raider, is readying the sale of its Nuaire business.

Last week, Electra shrugged off the attempt by American activist Edward Bramson to gain a seat on the board by reporting consensus-beating results and a 15pc rise in its portfolio value for the year.

The firm has hired advisers at KPMG to run a sale process for Caerphilly-based Nuaire, which Electra has part-owned since 2007 when it supported a management buyout. The business is expected to fetch between £150m and £200m.

Electra bought the business, which employs more than 400 people and has a turnover of more than £55m, from rival UK midmarket firm ECI.

Nuaire designs and makes ventilation systems for commercial buildings, houses and industry and recently benefited from a Welsh government grant to buy equipment. In July, Electra completed a £32.6m refinancing of the business with the Royal Bank of Scotland, which paved the way for a £15m return to the private equity firm. Electra declined to comment on the sale talks.

The firm, which recently bought The Original Bowling Company, said last week that it was in advanced talks with other acquisition opportunities which could see it spend around £300m in the next couple of months. The Daily Telegraph reported on Saturday that it was one of the three interested parties in final stages of bidding for American-themed restaurant T.G.I Friday’s.

In October, Electra shareholders voted against the attempt by Edward Bramson’s Sherborne Investors to gain a board seat but despite defeating the activist, the private equity firm announced that it would conduct a review of the fee arrangements, capital structure and distribution policy.