The takeover has been agreed after 35 organisations formally investigated an acquisition, with half actually submitting bids.

7IM was established in 2002 by its co-founders Justin Urquhart Stewart, Tom Sheridan and Charles Sparrow.

It started with seven founder members and has grown to a team of more than 190 people. At 30 April 2015, it had assets under management and administration of approximately £9.5bn.

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Caledonia will invest up to £77m in cash to acquire approximately 94% of 7IM Holdings, from its current owners, Allied Zurich Holdings and Aegon UK.

Tom Sheridan, 7IM's chief executive, said: “This year Zurich and Aegon appointed a corporate adviser to investigate the sale of their shares. The ensuing process is one that I have been personally very involved in.

“Thanks to the very strong support we have received from our customers, the business attracted lots of attention from prospective investors.

“Even after describing the profile of our preferred partner going forward, and thus ruling out many potential suitors, 35 organisations formally reviewed 7IM’s performance and plans. Among them were businesses from North America, Europe, Asia and Africa.

“There was a healthy combination of private equity and trade buyers. Half of them actually submitted bids to replace the current shareholders.”

7IM's management team will subscribe £5m for the remaining equity, with the balance of the purchase costs to be provided by £25m of bank debt, which Caledonia has agreed to underwrite in the event that this is not in place by completion.

Mr Sheridan said: "We are delighted to be partnering with Caledonia in the next phase of 7IM's development. Their investment philosophy and culture, as well as their attitude to longer term investment, are perfectly aligned with our own. This will enable us to continue our focus on and development of doing the right thing in our business, for not just our partners and staff, but of course most importantly our clients.”

Duncan Johnson, Caledonia's head of unquoted investments, said: "Caledonia has a long history of investing in successful fund management businesses. We look forward to supporting Tom Sheridan and his team in building on 7IM's impressive growth record and strong investment performance to service an expanding UK wealth management market where there is a growing demand for multi-asset and multi-manager funds."

The move is subject to the Financial Conduct Authority's approval.

For its financial year to 31 December 2014, 7IM Holdings reported profit before tax of £8.6m and gross assets of £42.9m.