On a walk this Friday with a group of other recent retirees in London we explored the two memorials in Trinity Square Park, just next to the Tower Bridge tube station and opposite Trinity House. One - a temple-like structure - is dedicated to and carries the names of all merchant seamen and fishermen who died at sea in WW1 and have no burial place, the second, a series of black panels carrying the names of the merchant seamen and fishermen who died in WW2 and likewise have no grave other than the sea, interspersed with white carvings. Two very moving memorials and a fascinating record, particularly for WW2.

See http://www.cwgc.org/find-a-cemetery/...ILL%20MEMORIAL - you may find the link useful to find other cemeteries/memorials.