A man has been charged on suspicion of causing criminal damage to a valuable painting at the National Gallery, Metropolitan Police said.
The National Gallery confirmed that the painting in question is The Morning Walk, by Thomas Gainsborough.
Keith Gregory, 63, of no fixed abode, was charged on Sunday March 19 following the alleged incident at one of London's best-loved galleries on Saturday afternoon.
The painting, which shows an "elegant young couple strolling through a woodland landscape", was attacked with a "sharp instrument" by a visiting member of the public, the gallery said.
It suffered "two long scratches which have penetrated the paint layers, but not the supporting canvas," in room 34 of the gallery's British Paintings exhibition.
The east wing of the gallery, in which the British Paintings are housed, was evacuated shortly after the alarm was raised at 2.15pm.
It was reopened two hours later.
The couple in the painting are thought to be William Hallett and Elizabeth Stephen, both aged 21 and "due to be married in the summer of 1785, shortly after the painting was completed," according to a National Gallery website page devoted to the work.
The painting has been removed from display by gallery conservators, who are assessing the next steps of a conservation effort to restore the work.
Gregory has been remanded in custody and is due to appear at Westminster Magistrates' Court on Monday, police said.