The IWGC sought advice on the form of the memorial from the seafarers' unions, who consistently requested a memorial in the form of a home for aged seamen or similar, but the commission was set against functional memorials in the belief that they became associated more with their function than with commemoration.
It rejected the request, overruling its own advisory committee in doing so, on the grounds that its charter did not allow it to fund the ongoing costs of an institution.
It insisted that merchant seamen would be commemorated on a monument.

The commission first intended to site the memorial at Temple Steps, on the bank of the River Thames, for which it commissioned Lutyens.
The architect designed a massive arch.
The proposed structure would have consisted of two 54-foot (16-metre) stone piers of linked, alternating arches (reminiscent of the Thiepval Memorial, which he was designing for the IWGC at around the same time) joined by a large beam, itself supported by two Doric columns between the arches.
This was approved by London County Council, but the Office of Works rejected it on the advice of the Royal Fine Arts Commission (RFAC), which objected on two grounds: first, that Lutyens' proposal would involve the demolition of an arch built when the Thames Embankment was constructed; and second, that the memorial would be better suited to a site further downstream, east of Tower Bridge, where it would be seen by ocean-going vessels which could not travel west of the bridge.
Both Lutyens and Ware attempted to persuade the RFAC to reconsider but to no avail.
Lutyens was furious, feeling that the merchant seamen had been relegated to "some hole in the corner because they happened to be low in social status", and that Sir Reginald Blomfield (a member of the RFAC and a rival of Lutyens) was acting out of spite.

Lutyens described the RFAC's opinion as "bosh", and suggested to Ware that they should continue regardless and force a confrontation.
Ware was more diplomatic, and the IWGC chose a new site in Trinity Square Gardens on Tower Hill, still west of Tower Bridge but further from the river.
This site was considered appropriate because it was within sight of the Thames, albeit not on the riverbank, and the area already had maritime connections, including the headquarters of the Port of London Authority at 10 Trinity Square, Trinity House, and the church of All Hallows-by-the-Tower (itself home to many nautically themed memorials).
Philip Longworth, in a history of the IWGC, remarked that the location meant that the commission's only memorial in London "would never be seen by most Londoners, still less find a place in the national consciousness as did Lutyens' stark monument on Whitehall" (the Cenotaph was not commissioned by the IWGC).

Trinity Square Gardens was Crown land administered by trustees.
Although the trustees suggested they would not object to the memorial, they did not have the power to give full consent and a special Act of Parliament was required.
The bill was laid before Parliament in December 1926 and received royal assent in June 1927, becoming the Mercantile Marine Memorial Act.
The building work was undertaken by Holloway Brothers (London) and the memorial was unveiled by Queen Mary (deputising for her husband, King George V) on 12 December 1928, her first solo engagement of the sort.
The unveiling ceremony was broadcast live on the radio in the queen's first use of the medium.
Despite taking place in torrential rain, the unveiling ceremony was attended by a large crowd, who cheered the queen as she was driven away.
The IWGC sought advice on the form of the memorial from the seafarers' unions, who consistently requested a memorial in the form of a home for aged seamen or similar, but the commission was set against functional memorials in the belief that they became associated more with their function than with commemoration. It rejected the request, overruling its own advisory committee in doing so, on the grounds that its charter did not allow it to fund the ongoing costs of an institution. It insisted that merchant seamen would be commemorated on a monument.
The commission first intended to site the memorial at Temple Steps, on the bank of the River Thames, for which it commissioned Lutyens. The architect designed a massive arch. The proposed structure would have consisted of two 54-foot (16-metre) stone piers of linked, alternating arches (reminiscent of the Thiepval Memorial, which he was designing for the IWGC at around the same time) joined by a large beam, itself supported by two Doric columns between the arches. This was approved by London County Council, but the Office of Works rejected it on the advice of the Royal Fine Arts Commission (RFAC), which objected on two grounds: first, that Lutyens' proposal would involve the demolition of an arch built when the Thames Embankment was constructed; and second, that the memorial would be better suited to a site further downstream, east of Tower Bridge, where it would be seen by ocean-going vessels which could not travel west of the bridge. Both Lutyens and Ware attempted to persuade the RFAC to reconsider but to no avail. Lutyens was furious, feeling that the merchant seamen had been relegated to "some hole in the corner because they happened to be low in social status", and that Sir Reginald Blomfield (a member of the RFAC and a rival of Lutyens) was acting out of spite.
Lutyens described the RFAC's opinion as "bosh", and suggested to Ware that they should continue regardless and force a confrontation. Ware was more diplomatic, and the IWGC chose a new site in Trinity Square Gardens on Tower Hill, still west of Tower Bridge but further from the river. This site was considered appropriate because it was within sight of the Thames, albeit not on the riverbank, and the area already had maritime connections, including the headquarters of the Port of London Authority at 10 Trinity Square, Trinity House, and the church of All Hallows-by-the-Tower (itself home to many nautically themed memorials). Philip Longworth, in a history of the IWGC, remarked that the location meant that the commission's only memorial in London "would never be seen by most Londoners, still less find a place in the national consciousness as did Lutyens' stark monument on Whitehall" (the Cenotaph was not commissioned by the IWGC). 
Trinity Square Gardens was Crown land administered by trustees. Although the trustees suggested they would not object to the memorial, they did not have the power to give full consent and a special Act of Parliament was required. The bill was laid before Parliament in December 1926 and received royal assent in June 1927, becoming the Mercantile Marine Memorial Act. The building work was undertaken by Holloway Brothers (London) and the memorial was unveiled by Queen Mary (deputising for her husband, King George V) on 12 December 1928, her first solo engagement of the sort. The unveiling ceremony was broadcast live on the radio in the queen's first use of the medium. Despite taking place in torrential rain, the unveiling ceremony was attended by a large crowd, who cheered the queen as she was driven away.
Tower Hill Memorial