Andrew Gabriel typed:

Im just suprised that the house being so solid appears to have
this weakspot. Is it just typical of houses of that era and
design?

I was a BCO in SW London for eight years: on my patch cavity walls
did not come into general use until the end of the 1930's,

Not in the 2 1/2 bed design from 1931 on, I still own two of these,
in fact my family built hundreds of these they were all cavity wall
construction. Must have been some real cheep-skate builders on your
patch.

Cavity walls go back before 1900 in some windswept coastal areas,
and gradually work their way across the rest of the country over
the following 40 or 50 years.

Yep a lot of Victorian houses on the south cost are built with a cavity but,
IIRC only a small gap and no wall ties.

--
Mark