The National Gallery has won its fight to keep the Renaissance masterpiece, the Madonna of the Pinks in Britain, it announced today.

The museum has been campaigning for 18 months to retain the tiny Raphael painting, since its owner, the Duke of Northumberland, agreed to sell the work to the J Paul Getty Museum in Los Angeles.

In January last year the National Gallery was given breathing space when the Department of Culture, Media & Sport slapped an export ban on the artwork going abroad.

Today, the museum, where the painting has been on long-term loan since 1991, announced that it had bought the canvas for £22 million.

Charles Saumarez Smith, National Gallery director, said that the deal was signed at 7.15pm yesterday.

The Inland Revenue will lose £13 million in the deal because the LA museum had offers of £35 million for the painting, the difference is the amount that the Duke would have had to pay in tax if he sold abroad.

As part of the agreement the Pinks will tour the country extensively and will be seen in locations including Manchester, Cardiff, Glasgow and County Durham.

The gallery receives £11.5 million from the Heritage Lottery Fund, £400,000 from the National Art Collections Fund and the rest from private and public donations.

Mr Saumarez Smith said: "The negotiations have been lengthy and have taken time but we are delighted to have secured the acquisition. We are immensely grateful to both the Duke and Sotheby's for helping to make the final agreement possible.

"It's a fantastic success that the sale has finally be agreed although all parties will probably agree that they wished it had not taken quite so long."

He admitted that the gallery was "extremely close to not getting agreement" and said the public's support was crucial and thanked them for their support.

"This is a picture which over the past year has had an incredibly high resonance with members of the public."

He said the Getty Museum had "withdrawn their application for the export licence last Monday. It became clear they weren't going to acquire the painting."