A sketch by Peter Paul Rubens, conservatively valued at $22.4 million, will go on permanent display at Tate Britain in London after a last-minute intervention by a public campaign to save the work.

The Apotheosis of James I, an oil on wood panel painting, was a preparatory sketch for designs Rubens later painted on ceiling canvasses at the Banqueting House in Whitehall between 1628 and 1630. The sketch depicts the ascent of King James I into heaven.

Tate Britain announced in a news release Wednesday that it had purchased the sketch for $11.1 million, thanks to an increase in pledges by the campaign's three chief donors — the National Heritage Memorial Fund, the Art Fund, an independent art charity, and Tate members — on deadline day.

The sketch has been in a private collection for 200 years. The vendor originally asked for $11.7 million but waived the final $600,000.

"It was a nail-biting finish," said Stephen Deuchar, director of Tate Britain. "We are thrilled to have achieved it."

Historian David Starkey joined the campaign in June when the sketch was united with the paintings of the Banqueting House ceiling for the first time. "The loss of the sketch would have been a fundamental betrayal of our national heritage and I am delighted it will remain on public display in London," he said in the release.

"The Banqueting House with its stunning Rubens ceiling is all that remains of the original Whitehall Palace after it was destroyed by fire in 1698," he added, "and this sketch is the key to the ceiling's composition."

The Apotheosis of James I was commissioned around 1628 while the Flemish master was visiting Britain as an ambassador for King Philip IV of Spain. The final nine canvasses were painted in Rubens' Antwerp studio and installed in Whitehall in 1638.