Macquarie Bank has agreed to buy NCP’s car-parks business from 3i Group, the private equity firm, for £790 million.

The deal gives 3i a 45 per cent return on its investment only 18 months after it took over NCP, the UK’s largest operator of car parks, from Cinven, a fellow private equity group, for £555 million.

The sale marks the third time that NCP has changed hands in less than five years.

3i will retain NCP Services, which runs enforcement services, clamping and removal and penalty charge processing as well as NCP's bus and coach operations, debt recovery and urban design consultancy.

The sale follows a period of rapid expansion of NCP under 3i’s ownership, the private equity group said.

It added that it had increased the number of employees at the group by nearly 20 per cent.

Macquarie is making the acquisition through its European Infrastructure Fund II, which also led the consortium that bought Thames Water, the UK's largest water group, from RWE, of Germany.

Car parks are popular with private equity firms because they have steady and highly profitable cashflow, underpinned by property assets that can be used as security against loans used to buy the business.

Macquarie is thought to have first tried to buy NCP 18 months ago, when the previous owner, Cinven, auctioned the business, three years after buying it in a hotly contested sale.

NCP was founded in 1931. It made a fortune from buying up cheap, bomb-damaged sites in London after the Second World War.

The business operates more than 900 car parks, including 52,000 spaces at ten of Britain's busiest airports, including Heathrow, Gatwick, Edinburgh and Aberdeen.

It also runs the contract for issuing penalty notices for London's congestion charge.

NCP manages 230,000 parking spaces and handles more than 60 million customer transactions a year.

Cinven bought NCP for £820 million in May 2002 from Cendant, of the US, which had bought the business in 1998 for £805 million.

Cinven released much of its capital via a sale and leaseback of more than 100 car parks, in a deal that raised £600 million.

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