There is a doctrine in UK copyright law known as "sweat of the brow". I imagine this is what the NPG's lawyers are referring to when they mention "painstaking

There is a doctrine in UK copyright law known as "sweat of the brow". I imagine this is what the NPG's lawyers are referring to when they mention "painstaking effort": http://en.wikipedia.org/wiki/Sweat_of_the_brow http://en.wikipedia.org/wiki/Sweat_of_the_brow