Bs 7671 doesnt state who is responsible....it states what is required.
Whoever carried out the installation would be responsible for complying with bs 7671.
Or, ....to a certain extent, whoever carried out any work on the installation last!!
So if the OP has undertaken any work on the installation knowing that main bonding wasn't in place he would take on at least a good portion of that responsibility of the installation NOT complying with BS 7671!!
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