On 28 September 1975, three gunmen led by Franklin Davies, a Nigerian, forced their way into the Spaghetti House restaurant in Knightsbridge, where the managers of the chain assembled weekly to deposit their takings (totalling £13,000 at that time). Nine Italian staff members were taken into the basement, whilst a tenth escaped unobserved and gave the alarm.

The Spaghetti House Police immediately surrounded and cordoned off the area. The gunmen, claiming to represent a 'Black Liberation Front', demanded safe release and an aircraft to fly them abroad. Sir Robert Mark, the Commissioner, in consultation with the Home Office (since foreign nationals were involved) refused.
Attempts were made to conduct hi-tech surveillance without the gunmen's knowledge. Dr Peter Scott gave invaluable psychiatric advice about the mental state of men cooped up under threat in uncomfortable conditions. Radio reporters demoralised the robbers with the insistence their demands would never be met, and the Daily Mail nobly suppressed a hard won scoop at Sir Robert's personal request, concealing the fact that the police had arrested a man they believed to be a confederate of Davies. The police ensured Davies received a false message to the effect that his alleged confederate was being paid for selling information to the newspapers, and this completed his demoralisation. The robbers emerged with their captives unharmed. The siege had lasted six days.