If were talking about tunnels.....
While not long or large tunnels the standard WW2 era JRC (like the one at Bicester or Azimghur Bks (ex RAF Colerne) had two Air Raid Shelters built into the basement, one at each end of the Bldg. The normal entrance is via a door at the bottom of the staircase at each end of the Bldg, stairs go down and then turn into the shelter. There is a escape tunnel at the opposite end which ran for about 50 mtrs to a vertical ladder going to a counter balanced hatch.
The 'Posh' double storey 'H' Blocks also had a similar set up, accessed via a door at each end of the central groundfloor corridor with a escape tunnel that runs away from the Bldg in line with the main doors to a escape hatch between 10 to 20 mtrs away from the Bldg.
The PSA and later on the Works Services EWC also had a 'Task' to carry out a Professional Inspection of all tunnels on a site, if they were there then I would expect a mention in the reports and Confined Space Registers.