I agree with kurnal, it is an issue that keeps on cropping up with enforcing officers using the guidance documents as law, which they are not. All the guides are there as a measure of best practice and in 99.9% of the time cover everything but the guides openly admit that they are not there to stop other solutions, it is just that it will be up to the project to prove that the measures taken will fulfill the obligations of the law which is to provide general fire precautions.
It is a battle that has been going on for a long time between people just push the codes and people looking at real risk assessment. A typical problem comes with travel distance where (for example) 18 m is the limit but the actual distance is 18.5m and someone starts insisting on measures to reduce the overall distance.