Staff at the National Gallery in Trafalgar Square have voted to go on strike in a row over the privatisation of services. The Public and Commercial Services union have said its members at the gallery supported industrial action by more than nine to one. The union warned walkouts were likely because of the opposition to privatising services such as security.
The capital's museums and galleries had record-breaking visitor numbers this summer.
Many of the attractions had their highest-ever monthly total in August this year - despite the warm weather which would usually keep people away while they enjoy the sun.
The Imperial War Museum welcomed more than 250,000 visitors as it helped to mark the centenary of the First World War.
And the National Gallery saw 681,000 pass through its doors - more than 100,000 above last August's figure.
The Director of the National Gallery, Dr Nicholas Penny has thanked the Van Gogh Museum for the unprecedented loan of a sunflower painting.
'This exhibition is designed to help those for whom the paintings by Van Gogh are compelling images to understand how they were made - and made again - and out of what materials' he said.
'It will deepen every visitor's appreciation of the artist. We are very grateful to the Van Gogh Museum for making this possible.'
Vincent Van Gogh started painting pictures of sunflowers in 1888 when he left Paris to live in the South of France.
He invited the artist Paul Gauguin to stay with him in a house he rented and painted the sunflowers which had been left in Gaugin's bedroom.
The five paintings he completed now reside in collections around the world in;
Two paintings of sunflowers by the post impressionist artist Vincent Van Gogh have gone on display at the National Gallery.
The paintings have been reunited for the first time in 65 years after the Van Gogh Museum in Amsterdam agreed to lend their painting to the Trafalagar Square gallery.