I've been looking at effects of tunnel settlement on some old piled structures East of London. The drawings (dated 1957) show a 'Holmpress' pile, described as a 14 inch diameter reinforced concrete cast in situ pile, with 40 ton load capacity. Has anyone any information on this pile type ? Onlt thing I could find was a 'Pressure Piling' type bored pile in a 1965 copy of "Oscar Faber's Reinforced Concrete". This used a compressed air lock on top of the pile.