This is the Belgian Navy frigate - Louisa Marie which arrived in London on Friday and moored alongside HMS Belfast.
It was carrying 70 bags of soil from WW1 Belgian Battlefields. During this Summer 1000 schoolchildren from the UK and Belgium helped to collect the soil and put it into bags made by the same Belgium company which supplied sand bags for the troops in the trenches almost 100 years ago.
Yesterday the bags were transported by the King's Troop Royal Horse Artillery through London to Wellington Barracks near Buckingham Palace. It is there that a memorial garden will be created using the soil. The garden will be open to the public next year.