Monument MPM2025 - Underground feature, St John's Road, Cosham

Underground feature discovered in a back garden in St John's Road, Cosham. The feature constisted of a short flight of steps which lead to what appeared to be a chamber/cavern. The chamber/cavern had been backfilled with soil and clinker to within about 60cm of the top and was not excavated. The stepped entrance had been backfilled with 20th century rubbish. The date and function of the feature could not be determined without archaeological investigation but it has been suggested that it may have been a Second World War air raid shelter.

Underground feature of unknown function discovered in a back garden in St John's Road, Cosham, in 2022.

That part of the feature that was uncovered consisted of a short flight of limestone steps (about 500mm rise between each step) cut through flinty chalk. The steps were level and had been set firmly into the subsoil. At a depth of around 2m, at a right angle to the steps, was an 'entrance' to what appeared to be an underground chamber/cavern. The latter had also been cut through the chalk and there was no evidence of brick or concrete having been used to strengthen it or the stepped entrance. The chamber/cavern had an arched roof and had been infilled with soil and black clinker to within about 60cm of the top. This feature was not excavated.

The stepped entrance had been backfilled with modern rubbish including a steel push-along lawnmower. The fill also contained a plastic 'Wonderloaf Bonus' wrapper (price 1/1), fragments of an earthenware hot water bottle with a screw stopper, bakelite electrical fuses and switches for round-pin plugs. This suggests that the feature was infilled during the 20th century.

The date and function of the feature could not be determined without archaeological investigation, but it has been suggested by the County Archaeologist that it may be a Second World War home dug air raid shelter. It is also possible that it may have served some other function. Prior to 1928 the land had been in use as an orchard.

HER Officer, 2022, Underground feature St John's Road, Cosham (Unpublished document). SPM603.