I read an interesting novel in about 1971 involving Tridents going to Moscow.
The story went the USSR managed to secrete an imitation nuclear device in the Houses of Parliament and challenged the British government to see if they could do something similar.
A plot was devised whereby the Moscow bound Trident would take off from Heathrow and would be stealthily joined by a Buccaneer carrying an imitation nuclear weapon. They would fly in close formation so as to present only one blip on radar, the Trident would somehow break off from the Buccaneer and land elsewhere (Copenhagen I think) and the Bucc would carry on on the flight planned route to deliver its payload in Red Square.
I don't remember the name of the book or who wrote it I'm afraid and some of the detail may be wrong, but in those days it was an intriguing tale!