James Amor wrote:
My question is - can anyone see a problem with (or had experience with)
using an adhesive and plugs/screws at 400mm centres to fix the aquapanel
straight to the brickwork? Aquapanel instructions are to fasten it at 600mm
centres, so adhesive plus smaller centres should be belt and braces
shouldn't it, or am I missing something?

I've fixed some Aquapanel directly onto a wall like that, and the
problem I found was the rather brittle panels developed stress fractures
anywhere the wall was even slightly out of true. You need the batons
to ensure that the fixing points of the panel are raised away from the
wall, and not causing unfixed areas to bow out and snap.
However, the batons could be very shallow - just a few mm would do.

It's also easier to plane or pack the batons to get a true line if your
wall is wonky, than trying to pack directly behind the aquapanel.

I would agree with fixing the panels at 400mm centres or less; I
noticed the panels would flex at 600mm.

Even so, I was more confident in the surface for tile fixing than onto
plaster, especially as I was replacing a terrible mess where the old
tiles were falling off the soggy, lumpy gypsum coat!

Vaci