Assuming the rules are the same in NI as England, correct. There has to be a time limit in these matters, and 35 years has to be way, way out of time;So Tony what you r saying here is that after work has been done over 12 months little authority can do??
I am in Northern Ireland and work was done 35 yrs ago
most inspectors would not even be familiar with the regs at that time, and it would entail them doing much research to check - just not worth the bother.