BS 5266-1 defines a competent person as someone with the relevant current training and experience, with access to the requisite tools, equipment and information so they are capable of carrying out the required tasks.
90% of EM installs we come across are non-complaint with regs. There is a real shortage of competency in this sector.
As a minimum, in order to carry out this kind of work competently you need to be fully versed with 5266-1, you need a light meter and know how to use it, you need some good software to aid with floor plans and calculation and you need your paperwork (risk assessments, O&M manuals, log books, photometric data, instructions etc...) to be in tip top condition.
You can't just sling a few EM lights in and hope for the best nowadays. If something went wrong and you hadn't designed and installed correctly, as you rightly assume, it'd be the dock you'd be stood in.