Vance had blamed Henry Nowak's death on the "mass invasion of migrants" - but Lammy says it "has got nothing to do with mass migration".
The Defence Investment Plan is now due to be released ahead of a Nato summit early next month.
The prime minister's position has hardened since Andy Burnham said he would seek to enter any potential Labour contest.
Harriet Sperling and Peter Phillips wed with King Charles, Queen Camilla and other royals attending.
A strengthening jet stream has brought rain to the UK but long-range summer forecasts show warmer weather could be ahead