As far as I understood it, anyone who does not complete and receive a satisfactory disclosure will have their pass removed by the BAA and will be dismissed.
The joke is foreign nationals working at the airport will get their disclosure back with "no record found" apparently. They show this to the BAA, who say "fine, carry on with your work". But someone who once got caught stealing a hot cross bun from the bakers when they were 16 could lose their job.
Only in the good old UK. There will become a time when the only people left working are coloured female lesbian single mothers with criminal records who have a current claim for ayslum being processed (no offence meant to any of those particular groups).