Disco 4SE, blown air intake manifold.

New manifold installed. Attached is a photo of repaired article, a bit rough due to access, but still serviceable after 2,625 km.
Attachment 147833

The crack seems to propagate from the circular hole - is there anything held in those holes or bolted through?

That hole seems like a bit of a stress raiser, especially if that area is fixed, and the rest of the manifold surface flexes due to intake air pressure and engine temperature.

I've just had a look at my manifolds and mine seem to be a different design.

Attachment 147839