On 02/12/2019 21:19, John Rumm wrote:
Made harder by being sunken in the shroud... You might be able to create
a couple of flats on either side with a needle file, then get pliers on
it.............

Not possible with the limited access.

You could also try some thermal shock - hold a bolt with pliers, and
heat the end blow torch and then push it onto the end of the screw for a
bit before trying to turn it................

Will give that go tomorrow

Personally I would probably try an anticlockwise drill bit just slightly
larger than the size of hole already in it.......

I dont have an anti clokwise bit.

It will either grab and spin
it out, and if not, it will take the head off, meaning you can remove
the tap handle and then worry about the shank of the screw after.

If the above fails I may try using a small drill bit to drill our a
couple of slots. The screw is brass so possible.