I also think it likely that the timing was connected with the G8 conference when security efforts had been diverted to Scotland
(opportunistic - not necessarily about G8, rather diverts our attention from important issues about distribution of wealth and about environmental protection)

The lastest news I heard said at least 38 have died, 100s are injured, some severly, and people who were due to have medical operations had to make way for the emergency cases.

An attack on transport services of a major city could kill and maim people of any nationality, creed and class.

(not particularly original perceptions)