It sets a new record for a piece of Titanic memorabilia, eclipsing the previous high of £100,000 paid for a set of the ship's postroom keys which were sold in 2007 by the same saleroom.
Offered with an estimate of £100,000-150,000, the plan sold to a UK private collector bidding by phone on May 28 - three days short of the centenary of the Titanic's launch at the Harland and Wolff shipyard in Belfast.
The 33ft (10m) longitudinal sectioned plan was commissioned by the British Board of Trade to assist in the 36-day inquiry. Headed S.S. Titanic Profile, the plan hung in the hearing room throughout the proceedings and was marked in red and green chalk to indicate where the ice was believed to have penetrated the liner.
The inquiry concluded that the loss of the ship had been brought about by "excessive speed". The unique plan was returned to White Star Line and then went into private ownership where it has remained ever since.
Auctioneer Andrew Aldridge believed a key factor in the success of the sale was the Daily Sketch's front page image showing the plan being used in the enquiry, illustrated here.
The buyer's premium was 10%.
By Gabriel Berner