LONDON, England - Dr Martens, the British footwear brand whose lace-up boots were made famous by punk music fans, has been bought by private equity firm Permira for 300 million pounds ($485 million).

The deal, expected to be finalised in January, will see the brand join Permira's portfolio of fashion labels such as Hugo Boss and New Look.

It is the second time Dr Martens has been put up for sale in the last two years, after the family-owned R Griggs held an auction that failed to attract enough bids.

Dr Martens chief executive David Suddens said the family had decided to sell for personal reasons, and wanted to invest their money elsewhere, without specifying.

"We are really very happy that is a private equity company that is investing in Dr Martens .... which will enable us to maintain the same culture we have had over the years and to look after the brand," Suddens told Reuters in a phone interview.

Under Permira, the brand expects to open more stores globally and develop new products areas, after seeing strong growth in its European, U.S. and Chinese markets.

Last year, Dr Martens posted sales of 160.4 million pounds and pretax operating profit of 22.9 million pounds, which it expects to grow to more than 30 million pounds in 2013.

Famous for their thick air-padded rubber soles and distinct yellow stitching, Dr Martens were favoured amongst workmen before being popularised by The Who's Pete Townshend in 1966.

Today, the brand's fans include singer Miley Cyrus who wears a pair in her latest music video Wrecking Ball.

Dr Martens boots were invented in 1947 by Klaus Martens, a German doctor who had a foot injury and created the air cushioned sole.

"Dr Martens is an iconic brand with a passionate fan base of followers," said Cheryl Potter, partner at Permira Funds.

"We are looking forward to supporting the management team in this exciting next phase of the company's development."

The move for Dr Martens is Permira's first investment from its latest - and fifth - buyout fund, and also marks its first buyout of a UK company since it bought Just Retirement in 2009.

Permira is still raising money for its fifth fund, and is targeting between 4 and 5 billion euros, less than the 6.5 billion it had originally hoped for when it announced fundraising in September 2011.