Clearswift, the digital security software company, has been acquired by London-based private equity firm Lyceum Capital for approximately £30 million.

The Berkshire-based company provides web and email security solutions for customers including BAE Systems, Hitachi Solutions, T-Mobile and Warwick District Council.

The new investment will enable Clearswift to grow its security software offerings and expand technically and geographically.

Most of Clearswift’s 170 staff are based in the UK, with some located at offices in Germany, Holland, Spain, Japan, the US and Australia.

Lyceum has acquired the majority stake in Clearswift from a group of investors including Amadeus Capital Partners, DFJ Esprit and Kennet. The former investors had held a stake in the company since 2002.

Individuals joining Clearswift’s board under the deal include Lyceum partners Jeremy Hand and David Harland, and software entrepreneur and former CEO of IRIS Software Martin Leuw, who will join as chairman.

Leuw said: "Clearswift’s content-aware, policy-based solutions are a key point of differentiation which enables over 17,000 organisations to manage and maintain no-compromise data, email and web security across all gateways and in all directions.

"With the backing of Lyceum Capital, who have an impressive track record of growing businesses, we will be well-equipped to execute an accelerated growth strategy."

According to Anthony Miller at analysts TechMarketView: "This is Leuw’s first appointment (and investment) since leaving Iris – and it is unlikely to be his last!"

Miller added that Clearswift made £16 million in revenue in the year to 31 March 2011, which was slightly down on the previous year. Less than 40 percent of the company’s turnover comes from the UK.

"Despite professing a recent return to profit, its company accounts still show a near-£2 million net loss, in what appears to be mostly attributable to intercompany bad debts in Australia and Japan," he said.