The main issue I was addressing was the fact that you seemed to be advocating a code 2 in some cases and a code 4 in others depending on installation date. I don't see why the coding should differ if the installation was done in 2008, 2006, or just landed in the street after falling through a gap in time and space!
But as you are questiong my justification for code 4, that is simply that it would have met the relevant British Standard the previous year and general attitudes to risk are slow to change*, and if it was acceptable in 2007, it shouldn't as be dangerous as to need improvement ASAP now!
If I was changing the board, then I would carry out the work to BS7671:2008, and as RCD protection is required for the lighting circuit in question, then I would no more fail to install RCD protection, than I would install a C32 MCB for it! (regardless of whether it was fused at whatever the fusing current of a paperclip is before or not
)
*the general attitude to risk changes over time, and common sense evolves with it, once upon a time we had cars without ABS, ESP, airbags, crumple zones, NCAP ratings, Pre-tensioners and even seatbelts themselves, and that was pretty acceptable at the time, but slowly but surly things have evolved, and those things are the norm on new vehciles these days (and common sense has changed these days...people drive worse because they feel the car will look after them)
Same with electric heaters, heating elements you could touch were acceptable at the time, people knew not to touch them!, but we have changed over the years, its a slow process though