After a 20-minute bidding contest on February 28, it sold to a phone bidder for £1m (plus premium), well above the £200,000-300,000 estimate.
In 1973-74, Enwonwu painted three versions of Tutu, an image that became a symbol of national reconciliation in the wake of the Nigerian-Biafran conflict.
However, all three paintings had been considered lost until specialist Giles Peppiatt made this discovery in a modest London apartment, where it had hung for the past 30 years.
Writing in the spring edition of Bonhams Magazine, the Nigerian-born novelist Ben Okri described the picture as “Africa’s Mona Lisa”, saying its emergence “amounts to the most significant discovery in contemporary African art in over 50 years”.
The Tutu series was of great personal significance to Enwonwu.
The first painting, executed in 1973, remained in the artist’s studio until his death in 1994. It was lost at some point after that, and its current whereabouts are unknown.
The location of the third Tutu painting is also a mystery, leaving the work for sale at Bonhams as the only known example of the image.
Works by Enwonwu dominated the sale, taking six of the top 10 prices.
It was broadcast live to a Bonhams event in Lagos, where bidders were able to take part in real time.