Would placing a dehumidifier in the room help with the drying out from
the inside?

if the interior is damp, then yes, it would reduce RH and thus speed
drying. If its not, because its just a small damp patch, then not
really.


Thats interesting - never occurred to me to use a dehumidifier. The
interior is not particularly damp, IIRC, so may not make a difference.


All sounds a bit complicated to me. Sort the downpipe out and you may
not need to do anything else.

Thanks - I think it will need repointing at the front (at least partly)
and anyway all the front paint needs stripped/sanded as it is in a
state anyway.

Thanks for all the advice from the other posters, too.