Perhaps it is just an in our face brag ... see we can get to you anytime we want. Making the point that all the tighter security could be penetrated at will.
Thus the two weeks to the day as well as similiar hour of day and the exact same number ... three trains and a bus just as it was two weeks age...
Makes Londoners nervous and unsettles some.
Doubtful it was a brag. Multiple witnesses saw the erstwhile suicide bombers backpacks explode - and then the fools ran away trailing wires, which I assume were for the detonators on their bodies. Kind of comical if you think about it.
So the bombers did intend to do something other than look silly.
Its beginning to sound a lot like a batch problem.