LONDON, ENGLAND - MARCH 9: British Prime Minister Theresa May arrives for the unveiling of the new memorial to members of the armed services who served and died in the wars in Iraq and Afghanistan at Victoria Embankment Gardens on March 8, 2017 in London, England. (Photo by Toby Melville - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 9:   British Prime Minister Theresa May arrives for the unveiling of the new memorial to members of the armed services who served and died in the wars in Iraq and Afghanistan at Victoria Embankment Gardens on March 8, 2017 in London, England. (Photo by Toby Melville - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 9: British Prime Minister Theresa May arrives for the unveiling of the new memorial to members of the armed services who served and died in the wars in Iraq and Afghanistan at Victoria Embankment Gardens on March 8, 2017 in London, England. (Photo by Toby Melville - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 9:   British Prime Minister Theresa May arrives for the unveiling of the new memorial to members of the armed services who served and died in the wars in Iraq and Afghanistan at Victoria Embankment Gardens on March 8, 2017 in London, England. (Photo by Toby Melville - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 9: British Prime Minister Theresa May waves as she leaves after the unveiling of the new memorial to members of the armed services who served and died in the wars in Iraq and Afghanistan at Victoria Embankment Gardens on March 8, 2017 in London, England. (Photo by Toby Melville - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 9:   British Prime Minister Theresa May waves as she leaves after the unveiling of the new memorial to members of the armed services who served and died in the wars in Iraq and Afghanistan at Victoria Embankment Gardens on March 8, 2017 in London, England. (Photo by Toby Melville - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 9: British Prime Minister Theresa May, Secretary of State for Defence Michael Fallon and Chief of the Defence Staff Air Chief Marshal Sir Stuart Peach attend the unveiling of the new memorial to members of the armed services who served and died in the wars in Iraq and Afghanistan at Victoria Embankment Gardens on March 8, 2017 in London, England. (Photo by Toby Melville - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 9:   British Prime Minister Theresa May, Secretary of State for Defence Michael Fallon and Chief of the Defence Staff Air Chief Marshal Sir Stuart Peach attend the unveiling of the new memorial to members of the armed services who served and died in the wars in Iraq and Afghanistan at Victoria Embankment Gardens on March 8, 2017 in London, England. (Photo by Toby Melville - WPA Pool/Getty Images)