The painting, the only Orazio Gentileschi work in a UK public collection, has been on loan to the gallery since 2002.
However, Kirkham is selling part of his collection, having put five Old Masters up for sale at Sotheby’s in July.
For 12 years, Orazio Gentileschi lived in London as a court painter to King Charles I. The Finding of Moses was commissioned to celebrate the birth of the future Charles II and was intended to hang in the Queen’s House at Greenwich.
Kirkham acquired the painting in 1995 from Castle Howard in Yorkshire, at Sotheby’s for £5m.
The cost of acquiring The Finding of Moses now is £22m, though the net cost to the gallery would be £19.5m through a private treaty sale being arranged by Sotheby’s and Pyms Gallery.
The National Gallery, which has already raised £17.5m to fund the acquisition, described the painting as being “of outstanding importance for the national heritage” given its links to this country.
It is the painting’s “monumental scale (257 x 301cm), extraordinary ambition and historical importance that sets The Finding of Moses apart,” the gallery said.
In 2018 the gallery acquired a painting by Orazio’s daughter Artemisia, Self-Portrait as Saint Catherine of Alexandria.
Grants towards this purchase include £2.5m from the National Heritage Memorial Fund and £1m from Art Fund.
Donations to the appeal can be made in the following ways:
- Online at www.nationalgallery.org.uk/saveorazio
- Telephone: 020 7747 5982
- Cheque to Freepost RTLK-HERE-JSKB, Ms Stéphanie Gaillard, The National Gallery, London WC2N 5DN.