Drainage / downpipe problems...?

[dbrb2]

I have a victorian, largely dry house (the blue one) - except for the corner shown below, by the white coins.
The concrete in the garden is higher than the ground level of the rest of the house, and the crack in that concrete ends almost exactly where I see my damp.

There is also a downpipe going into the ground which may or may not drain somewhere unhelpful

I've been talking to various people about a fix - and the suggestions seem to fall into two camps:

French drain up against the side of the house
Similar, but aco drain instead

Does anyone have any experience of something similar?

Cheers!

 

[datarebal]

The lowest visible quoin looks like it's in trouble probably doesn't help things .
As far as downpipe is concerned the picture doesn't show enough