Treating damp at window area

I am moving into a refurbished cottage, which is maybe 40 years old or so. There are double glazed windows fitted, but at a bay window, there is damp. It appears to be caused by rain driven in from the outside at the part where the window joins the wall. (It is not rising up from the ground.) The damp is not too bad, but it is there nonetheless.

The house seems to be of concrete construction (don't know exactly if it is mass concrete or block built), I don't imagine there is a vertical damp-proof course.

Any ideas on what I should do to treat it?

Thanks for your help!