On my own pc I'm receiving UK targeted adverts - but on another pc elsewhere in the UK, its getting US adverts.
I did a search on both PCs for loan
on mine - three sponsored results in blue at the top - all co.uk
on the other pc - no sponsored results at the top - all the results on the right are for US companies - some using $ in the adtext.
to my knowledge the pc receiving the US ads has been online for several days, so there's been no IP change or anything like that.