The current edition of approved document P basically seems to say "follow BS7671"....
It does, which is why I said that's what a BCO would look to - but everything (including that) in the Approved Doc is presumably covered by the initial statement that "there is no obligation to adopt any particular solution contained in an Approved Document if you prefer to meet the relevant requirement in some other way.".
, though interestingly it reffers to "BS 7671:2008 incorporating Amendment No 1:2011." not to the current version of the standard...................
Yes, legislation and related things (like these Approve Docs) always seems to do that when it refers to some other Standard/ Regulations/ whatever - e.g. the recent 'PRS' legislation refers specifically to BS7671:2018 - which means that they have to amend the legislation/document if they want to update the reference to relate to a new version of the Standard/whatever.
In this case, they've obviously chosen not to do that, since the most recent version of Approved Doc P is that issued in 2013, so it necessarily cannot refer to anything more recent than the 2011 Amendment of BS7671:2008. That could result in some interesting situations if the BCO decided that compliance with that obsolete edition of BS7671 was what is currently required to satisfy the law
In relation to legislation, I once asked a lawyer why they do it like that. She said that she thought the reason was that legislators did not want to refer to things that had not yet been published - just in case it transpired that, when they
were published, the legislators did not agree with them - i.e. if they wrote "the current edition of BS7671", they would effectively be writing a 'blank cheque' in relation to what future authors of BS7671 decided to write in the future ... but goodness knows whether there is any truth in that!
Kind Regards, John