files marked with a "Christmas tree"
... that throughout the Cold War, "subversive" persons at the BBC had their files marked with a "Christmas tree"?
... that throughout the <a href="./Cold_War" id="mwAUo" rel="mw:WikiLink" title="Cold War">Cold War</a>, "subversive" persons at the <a href="./BBC" id="mwAUs" rel="mw:WikiLink" title="BBC">BBC</a> had their <b id="mwAUw"><a href='./"Christmas_tree"_files' id="mwAU0" rel="mw:WikiLink" title='"Christmas tree" files'>files marked with a "Christmas tree"</a></b>?