Hundreds attend a dedication service at the National Memorial Arboretum for the Elysium Memorial.
High construction costs and the Iran war are threatening the key manifesto pledge, the housing secretary says.
The individual worked at the US embassy in Vauxhall, south London, had diplomatic protection, despite not being a diplomat.
This year's event sees 63,000 people take on the half marathon - including the prime minister.
A review of constituencies used in May's Welsh Senedd could see Welsh-only names changed.
The woman, 19, and man aged 21, were detained on Friday after the girl's death in Atherstone.
