Santa Claus and satire, postmen and prisoners – these are tiles in the rich mosaic of stories produced by Palestinian playwrights, given the prompt to write on whatever they want. These stories form part of Tomorrow Will Be A Palestinian Day, a showcase of nine short works by playwrights from Palestine and in exile, performed by an all-Palestinian cast, being put on at Theatre503 in London in early June. The show's cornerstone is the English-lan…