For some strange reason I saw this on ebay and thought of Jem.
//http://cgi.ebay.co.uk/ROC-Nuclear-Bunker-Master-Post-Peak-District_W0QQitemZ330408714804QQcmdZViewItemQQptZUK_HG_Property_RL?hash=item4cede4e234#ht_1364wt_1167
Could of been the Sunken Cube
//http://cgi.ebay.co.uk/ROC-Nuclear-Bunker-Master-Post-Peak-District_W0QQitemZ330408714804QQcmdZViewItemQQptZUK_HG_Property_RL?hash=item4cede4e234#ht_1364wt_1167
Could of been the Sunken Cube