On 23/10/2019 11:04, John wrote:
My daughter's house has a rather nice walled garden - but the wall has no
capping and some of the bricks are spalling. The wall is a brick length
thick - with the top of the wall laid with bricks across it.

I really feel we need to put some capping on the top to prevent more water
and frost damage.

What would you suggest? Glazed brick? Stone?

Could the wall be cleaned as it looks a bit stained from water soacking
down it?

Coping stones. Wire brush or if necessary brick acid for the stains.