British High Commission Press Release, 8 Feb 08:

Scotland Yard Report Into Assassination of Benazir Bhutto Released
In his report Dr Cary states:

• “the only tenable cause for the rapidly fatal head injury in this case is that it occurred as the result of impact due to the effects of the bomb-blast.”

• “in my opinion Mohtarma Benazir Bhutto died as a result of a severe head injury sustained as a consequence of the bomb-blast and due to head impact somewhere in the escape hatch of the vehicle.”

Given the severity of the injury to Ms Bhutto’s head, the prospect that she inadvertently hit her head whilst ducking down into the vehicle can be excluded as a reasonable possibility.

High explosives of the type typically used in this sort of device, detonate at a velocity between 6000 and 9000 metres per second. This means that when considering the explosive quantities and distances involved, such an explosion would generate significantly more force than would be necessary to provoke the consequences as occurred in this case......
and:
There has been speculation that two individuals were directly involved in the attack. The suggestion has been that one suspect fired shots, and a second detonated the bomb. All the available evidence points toward the person who fired shots and the person who detonated the explosives being one and the same person.

• Body parts from only one individual remain unidentified. Expert opinion provides strong evidence that they originate from the suicide bomber.

• Analysis of the media footage places the gunman at the rear of the vehicle and looking down immediately before the explosion. The footage does not show the presence of any other potential bomber.

• This footage when considered alongside the findings of the forensic explosive expert, that the bombing suspect was within 1 to 2 metres of the vehicle towards it rear and with no person or other obstruction between him and the vehicle, strongly suggests that the bomber and gunman were at the same position. It is virtually inconceivable that anyone who was where the gunman can clearly be seen on the media footage, could have survived the blast and escaped.

The inevitable conclusion is that there was one attacker in the immediate vicinity of the vehicle in which Ms Bhutto was travelling.