Investors who were duped into ploughing funds into a luxury homes project that ultimately failed have been awarded costs including an interim payment of £1.1m.

A multi-million-pound civil case focused on grade 1-listed Cornwall Terrace on the edge of London’s Regent's Park.

Developers Oakmayne, or the Oakmayne Group, were behind a scheme to convert the building to prime residential properties to sell to high-net-worth individuals.

Claimants Matthew Wickers, Dennis Lavin and John Tinsley were persuaded to invest sums totalling £1.2m, £1.25m and £1m respectively.

Each of them lost their money when the project failed.

Judgment handed down in June following a six-week trial last year concluded they had been duped into investing in the project.

Deemster Alan Gough found that the investment opportunity brochure was a ‘fraudulent document’ which mis-stated facts and deliberately omitted or disguised matters, not least the £3,763,735 success fee.

Island-based defendants, David Humbles, Michael Riddell and Guy Wiltcher were all directors of OPR, which is now in liquidation, have now been ordered to pay costs.

The claimants had estimated their costs at £2.5m but the Deemster reduced this to £2.25m taking into account that while their claim which was predominantly successful, part of it was not.

He ordered an interim payment on account of costs in the sum of £1.1m plus VAT to be paid within 28 days.

The Deemster ordered that interest on the judgment sums be paid at 4% per annum from the date of each loss to June 2019 and at 8% per annum from that date to the date of judgment.

Cornwall Terrace on the edge of London’s Regent's Park was constructed between 1821 and 1823 to a design by Decimus Burton.

Oakmayne’s development project was hit by increased building costs and construction delays, leading to its failure with losses of £43m.