Insulating concrete formwork

The insulating concrete form 1 for forming a poured concrete wall has an exterior wall surface 2 comprising an insulating panel and an interior wall surface 3 comprising a rigid panel. One or more connectors 4 engage with the insulating panel and the rigid panel to define a cavity into which concrete can be provided. The insulating panel may be made from a phenolic foam and have one or more projections 13 which, in use, reduce to amount of concrete required to fill the cavity. The rigid panel may be a high impact plaster board panel and may be provide with utilities conduits. A connector, an insulating concrete formwork system, a wall formed by the system and a method of constructing a building using the concrete formwork are also claimed.