A charity cleaning the River Thames in central London last week found four unexploded bombs.
Volunteers from anti-litter charity Thames21 found the shells by London Bridge. The Marine Support Unit of the Metropolitan Police was called in to take them away.
An unusually low tide revealed the shells in a usually unexposed part of the river bed. Victor Richardson, enhancement co-ordinator at Thames21, said: "The rain was beginning to dampen spirits until someone found the shells - they certainly got the blood pumping again."