bjcc
At great risk of thread creep.
The "Due Dilligence" process has been agreed with Her Majesty's Inspector of Railways", as being acceptable and they will not pursue a S28 Prosecution with it in place.
The "Due Dilligence" process is also contained within each railway Operators Railways Safety Case in accordance with the Railways (Safety Case) Regulations.
We as the Industry would not 'test' this, neither by agreement will HMRI.