"Christmas tree" files

From the 1930s until the 1980s, the BBC kept a number of clandestine files on applicants accused by MI5 of political subversion, in particular those deemed to be communists or fellow travellers of communism, and also members of far-right organisations.

They were marked with a distinctive upward-facing green arrow, which bore resemblance to a Christmas tree and had the effect of blacklisting a number of applicants for roles in the BBC.

During World War II, those deemed to be political subversives, in particular suspected communists or fellow travellers of communism, were banned from working at the BBC.

The personnel records of anyone suspicious were stamped with the legend "SECRET", a distinctively shaped green upward-facing arrow resembling a Christmas tree.

[6][better source needed] Michael Hodder, who worked for the vetting unit in the 1980s, told The Times that all files were destroyed in the early 1990s as the Cold War ended.

Despite an alliance with the Soviet Union during the Second World War since 1941, suspected communists who applied for work at the BBC were investigated by MI5 officers (poster produced by the Communist Party of Great Britain )