A Party Wall Surveyor acting for a neighbour has quoted the following figures (as 'market rates') for the formation of a 10m x 3.5m reinforced basement wall in central London. The figures seem a bit steep to me; just want to see what others think...
underpinning £500/m2
excavation £200/m3
propping £200/m
underpinning £500/m2
excavation £200/m3
propping £200/m