On Wed, 5 Aug 2020 10:25:32 +0000 (UTC), RJH wrote:

It's paint on an external brick wall, a skin of emulsion like paint on
top of rock hard masonry paint. It scratches off with a finger nail, but
is annoyingly hard to remove from this large area (about 60m2). It's
just this skin of paint I want to remove - I'll take my chances on
what's underneath when I come to repaint the walls.

Pressure washer. Will remove anything remotely loose. Messy though,
put a tarpualin on the ground under where you are working and a
couple yards each side. Also one behind you to contain (most of) the
flying bits.

--
Cheers
Dave.