The HSE investigation focussed on the possibility of a faulty gas distribution system and found the cast iron mains pipe was sunk in sandy-gravelly soil that was classified as "very aggressive" to "moderately corrosive".

BBC: Shrewsbury gas explosion 'no-one's fault' HSE concludes

The corrosive nature of the ground soil and pressures from a nearby brick wall and telecom unit may have caused a fracture in the cast iron mains pipe, the HSE said in its report.

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