[color=blue]1) During my stay in London, he was the first person to invite me to their house.
[color=indigo]2) In London, he was the first person to invite me to their house.
[color=darkblue]3) He was the first person to invite me to their house, in London.
[color=red]4) He was the first person to invite me to their house in London.
I think in the last one ‘in London’ modifies ‘his house’.
In ‘3’, ‘in London’ seems to have been added as an afterthought.
Gratefully,
Navi.