The nine-strong group made the trip as it marked 99 years since the landings on the Gallipoli Peninsula in 1915.
In both New Zealand and Australia the day not only commemorates those first landings but also all those who have given their lives in the service of their countries.
The service was conducted by the Dean of Westminster and attended by the Duke of Gloucester, the Lord Mayor of Westminster and the High Commissioners for New Zealand and Australia.
The muster of ex-servicemen and women from Australia and New Zealand, together with veterans from Britain, marched past the Cenotaph, into Horse Guards and on to the abbey. The ex-Merchant Navy veterans from Gravesend joined the march and the congregation.
Gravesend Merchant Navy Association is a small band of ex-merchant seamen, and their wives, who are active in the area.
They have been invited to parade standards at many civic events in the town and also the RAF Battle of Britain commemoration at Capel-le-Ferne each year.
The Merchant Navy memorial in Gravesend is at Bawley Bay on the riverfront next to the St Andrew’s Arts Centre.
Anyone with a connection to the river or the merchant fleet is welcome to join.
They meet on the last Saturday of the month at the Waterloo pub in Wellington Street.