The walls are adjoining walls (as mentioned the one side backs onto the
passage and is therefore sheltered.
I havent yet found a pattern. There were damp patches whilst the house was
unoccupied, so it is not purely down to cooking etc. However having said
that,
Dampness does seem worse after cooking, but my feeling is that this area is
already damp, and so may be attracting any additonal humidity.

Are the wall/s adjoining walls or are they gable end walls?

When you say "come and go" have you noticed any particular instance of
them
reappearing? ie they appear when it rains,they appear when your're cooking
or after?
Usually the problem can be narrowed down if you notice the conditions the
damp appears.
For instance a blocked chimney after a downfall some of the rain could be
getting down it and settling in/on the blockage then seep through the
brickwork,if you don't have a cowling on the chimney stack? then fit
one,Im
not saying this is the likely cause but no one can give a definate answer
to
the problem without actually seeing it when it occurs.