Now, TheBox appears to be really closing for good. The day after they "closed" last time, they simply moved to a cryptic non-.uk domain name, and they apparently got rid of some undesirable types and those with low ratios, and membership was by invite only.
But after almost a year, they say they're gone for good as of August 1. The loss of access to classic UK material, much of which was never released on home video (especially in the USA), will be sad.