Scotland Yard says it is "too early to speculate" on Russian reports that the attack could be a gangland hit linked to a murder attempt on another banker, Alexander Antonov, in Moscow.
The force's Trident command - which investigates gang shootings - is understood to have liaised with overseas counterparts in the hunt for the gunman behind the attack on Tuesday evening.
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Through the rest of today showers will continue across many northern areas, whereas for much of England and Wales it'll stay largely dry.