Corrected entry: The reference to the UK needing special "secret launch codes" from the UN is a compete fiction. The UK could launch a nuclear strike without needing permission from the UN. The UK would, however, need permission from the United STATES [not United NATIONS] to launch a nuclear strike, as the Polaris missiles are leased from the US Government [although the UK owns the warheads].
Corrected entry: After the Slitheen realize that the Doctor's ruse with the alcohol is a ruse, the metal shielding around the windows and doors slams shut quite quickly. Later, while talking with the Slitheen again, the shielding closes much slower. Seems like their motors run at speeds determined by the dramatic tone of particular scenes.