The approach, worth pounds 10 a share, trumps a 925p offer for Mersey Docks tabled last month by the private equity firms CVC Capital Partners and Cinven. Mersey Docks shares closed at 998p.
Peel Holdings already has a 25.66 per cent blocking stake in Mersey Docks which it could use to prevent CVC and Cinven from acquiring the company even if they came back with a higher offer.
Sources close to Mersey Docks said that the offer of pounds 10 a share would be acceptable to the company, although a formal bid is still at least a month away. Peel Ports, the subsidiary of Peel Holdings which made the approach, is about to start due diligence.
Mr Whittaker, 62, is one of the North-west's wealthiest property magnates but maintains a low profile. He does not have a Who's Who entry and lives on the Isle of Man. He took Peel Holdings private last year.
Peel Holdings' other interests include Clydeport, which it took control of in 2002, and the Trafford Centre retail development in Manchester. It is thought to be interested in Mersey Docks primarily because of the development potential of a one-and-a-quarter mile stretch of waterfront land next to the Mersey estuary owned by the company.
Mersey Docks, which also owns Medway port in Kent and port facilities in Heysham, has benefited in recent years from the surge in world trade and now accounts for a quarter of all container traffic between the UK and North America.
Peel took its shareholding in Mersey Docks above the 25 per cent level just over a week ago, shortly after the company announced the 925p approach from CVC and Cinven.
Because Mersey Docks is incorporated under an Act of Parliament any takeover would have to be structured as a scheme of arrangement which requires the support of 75 per cent of shareholders.Reuse content