Observation and common sense led me to my original conclusions which
have been roundly deconstructed above. periodproperty has been tried
and they were of no use unfortunately other than to suggest taking the
concrete floor up which I would like to do but it's a job a bit beyond
my means. i think reinjecting is the answer. in the meantime we have
tracked down the builder who did the original dpc in 92. he is retired
but is happy to come and have a look....