On 02/12/2019 22:00, The Natural Philosopher wrote:
Impact driver

Dont have one but could I suppose try using cordless drill on hammer,
has worked before for me. OR if needs be use a crosshead bit and thump
it with a hammer.

I will look at all suggestions and go from gentle to not so gentle and
then destructive, assuming if I destroy the screw head then the shroud
will come off and then can tackle the remains of the screw, which by
then will give me better access.