Early 70s house, gable ended roof made from prefabricated trusses.

I have a problem with condensation in the roof space. I suspect the
house was probably OK as built but since then previous owners have
fitted double glazing which I assume has reduced the ventilation and
resulted in more moisture in the air. Also a double thickness of loft
insulation (the second layer looks quite recent) meaning, I assume,
the roof space is colder than before and more liable to condensation.
The underside of the felt is damp and where nails poke through they
have a drop of water on the end. Storage boxes have gone soft.

I started fitting soffit vents but had access problems and decided to
look and see if I could fit them from inside. I realised that the
insulation was tucked right into the corners effectively blocking any
airflow from the eaves. On rolling back some of the insulation I see
that the outer leaf of bricks has been built up between each truss so
that it comes right up to the roofing felt. An even more effective
block to any ventilation.

Is this normal practice? The cutting of the bricks and cement work
looks a bit gash between the trusses so I wonder if it was a bodge by
the previous owner to keep birds out.

Should I just remove these extra bricks and allow airflow through the
soffit vents?

A previous house had an airbrick high up in each gable end. Would that
be a good solution?

Andrew