As with any building work, finding evidence of past life and indiscretions is not uncommon, especially in town parks.
Dallan Tan, from the Association of Play Industries, says he has found "vintage whisky bottles, railway sleepers, barbed wire, sex toys and a gun, but never bombs" while installing play equipment.
Companies today would usually check if there had been "any military or industrial activities on the site" he says.
They would also do dig tests and CAT (Cable Avoidance Tool) scans, but in the 1980s, when the park was first installed, "health and safety standards would have been very different".
"I don't think anyone is to blame, they were just really, really unlucky."