Alastair MacLean novel, (c)1962, originally published as by
Ian Stuart.
Morden is a biowar recearch facility in England. They have recently developed a virus with the potential to nuke the human race. Now the Satan Bug has been stolen. The kicker is that the terrorist who has stolen it is actually a thief, and the purpose of the whole thing is simply to cause the evacuation of London so the gang can clean out the financial district...
This plot device was used in an episode of Nash Bridges. One hopes they at least thought it was an original idea...