Of course the visual could have some place in a plan
The problem with the "thingy2 as I like to call it for derogatory purposes,is that it is not an inspection and test as per the good book.
It is however,a very easy simple tool that a dodgy or even an ignorant landlord could use instead of a proper testing regime,(which is possibly the best way of a landlord passing responsibility of his duty of care to another party) and being in a strong position should any incident occur
The only problem with my above statement that I see,is the actual pir can and very often is carried out by electricians who may not be competent to do so
The main culprit with that is the Niceic, who use the dangerous qualified supervisor systen, where an unskilled person can and often is sent out on these missions
Then you have the crap pir to show, that may exclude you the landlord from the courts wrath,but betrays the safety of the tennant
If you are genuine in your desire for a safe installation,forget the myth and nonesense that an Niceic Pir is the one to get, and instead insist on the electriocian, who actually will be doing the testing and inspection,make sure he is qualified (2391 perhaps)and experienced
A labourers inspection signed by a guy in an office who may have never seen the installation is as much a fake as the visual "thingy"