A pod of porpoises has swum up the Thames to central London.
The Metropolitan Police Marine Policing Unit has been following the group of mammals, which may have been attracted to the relative shelter of the river because of the tidal surge and weather.
Initially the river patrol team, reported a sighting of a dolphin at Tower Bridge but further updates revealed them to be harbour porpoises, which usually stick to coastal areas and river estuaries.
The Marine Policing Unit tweeted: “Marine 2 are following a pod of about 5 harbour porpoises in the Lambeth area of the river.”
It later added: “The porpoises seem happy enough. They are surfacing regularly and are staying in the Westminster area.”
A Marine Conservation Society spokesman said: “The pod should be able to navigate back to sea, and pass through the Thames Barrier when the tide goes out and the barriers are opened.”